A large quantity of the salt is now prepared from the "spent oxide" of the gas works, the cyanogen compounds formed in the manufacture of the gas combining with the ferric oxide in the purifiers to form insoluble iron ferrocyanides.
A similar behaviour has since been noticed in other trimethylene derivatives, but the fact that bromine, which usually acts so much more readily than hydrobromic acid on unsaturated compounds,, should be so inert when hydrobromic acid acts readily is one still.
A summary of its chemical transformations may be given here, and reference should be made to the articles on the separate compounds for further details.
About the same time he showed by a wonderful series of experiments that the colouring matter of Prussian blue could not be produced without the presence Of a substance of the nature of an acid, to which the name of prussic acid was ultimately given; and he described the composition, properties and compounds of this body, and even ascertained its smell and taste, quite unaware of its poisonous character.
According to Gerhardt, the process of substitution consisted of the union of two residues to fo- m a unitary whole; these residues, previously termed " compound radicals," are atomic complexes which remain over from the interaction of two compounds.
According to Liebig, potassium is the essential alkali of the animal body; and it may be noted that sheep excrete most of the potassium which they take from the land as sweat, one-third of the weight of raw merino consisting of potassium compounds.
According to this theory a " chemical type " embraced compounds containing the same number of equivalents combined in a like manner and exhibiting similar properties; thus acetic and trichloracetic acids, aldehyde and chloral, marsh gas and chloroform are pairs of compounds referable to the same type.
According to this view, it is necessary to assume that, in all unsaturated compounds, two, or some even number of affinities are disengaged; and also that all elements which combine with an even number of monad atoms cannot combine with an odd number, and vice versa, - in other words, that the number of units of affinity active in the case of any given element must be always either an even or an odd number, and that it cannot be at one time an even and at another an odd number.
Acetylene is readily decomposed by heat, polymerizing under its influence to form an enormous number of organic of compounds; indeed the gas, which can itself be directly prepared from its constituents, carbon and hydrogen, under the influence of the electric arc, can be made the startingpoint for the construction of an enormous number of different organic compounds of a complex character.
Acridine and its homologues are very stable compounds of feebly basic character.
After having been somewhat neglected for the greater attractions and wider field presented by organic chemistry, the study of the elements and their inorganic compounds is now' rapidly coming into favour; new investigators are continually entering the lists; the beaten paths are being retraversed and new ramifications pursued.
Again, fluorine shows a great tendency to form double salts, which have no counterpart among the compounds formed by the other members of the family.
Again, when tungsten hexachloride is converted into vapour it is decomposed into chlorine and a pentachloride, having a normal vapour density, but as in the majority of its compounds tungsten acts as a hexad, we apparently must regard its pentachloride as a compound in which an odd number of free affinities are disengaged.
All thallium compounds volatile or liable to dissociation at the temperature of the flame of a Bunsen lamp impart to such flame an intense green colour.
All these cases of solution are to be distinguished from chemical compounds on the one hand, and from simple mixtures on the other.
Although algae generally are able to use carbonic acid gas as a, source of carbon, some algae, like certain of the higher plants, are capable of utilizing organic compounds for this purpose.
Amidotetrazotic acid yields addition compounds with amines, and by the further action of nitrous acid yields a very explosive derivative, diazotetrazol, CN 3.
Amino-azo Compounds may be prepared as shown above.
Ammonium uranate heated to redness yields pure U308, which serves as a raw material for uranium compounds.
Among the Arabian and later alchemists we find attempts made to collate compounds by specific properties, and it is to these writers that we are mainly indebted for such terms as "alkali," " sal," &c. The mineral acids, hydrochloric, nitric and sulphuric acids, and also aqua regia (a mixture of hydrochloric and nitric acids) were discovered, and the vitriols, alum, saltpetre, sal-ammoniac, ammonium carbonate, silver nitrate (lunar caustic) became better known.
Amongst endothermic compounds may be noted hydriodic acid, HI, acetylene, C 2 H 2, nitrous oxide, N 2 O, nitric oxide, NO, azoimide, N 3 H, nitrogen trichloride, NC1 3.
Amorphous carbon is obtained by the destructive distillation of many carbon compounds, the various kinds differing very greatly as regards physical characters and purity, according to the substance used for their preparation.
An ethylenic or double carbon union in the aliphatic hydrocarbons has, apparently, the same effect on the boiling-point as two hydrogen atoms, since the compounds C 0 H 2 „ +2 and CoH2n boil at about the same temperature.
An important class of compounds, termed amines (q.v.), results from the condensation of alcohols with ammonia, water being eliminated between the alcoholic hydroxyl group and a hydrogen atom of the ammonia.
An important group of soil organisms are now known which have the power of using the free nitrogen of the atmosphere for the formation of the complex nitrogenous compounds of which their bodies are largely composed.
Analysis, &c. - All volatile potassium compounds impart a violet coloration to the Bunsen flame, which is masked, however, if sodium be present.
Analytical Chemistry This branch of chemistry has for its province the determination of the constituents of a chemical compound or of a mixture of compounds.
Analytical problems, such as the isolation of certain organic radicals, attracted his attention to begin with, but he soon turned to synthetical studies, and he was only about twenty-five years of age when an investigation, doubtless suggested by the work of his master, Bunsen, on cacodyl, yielded the interesting discovery of the organo-metallic compounds.
And from the study of compounds he showed that each element occurred in a definite weight or in some multiple of this weight.
And it remains to be seen, how far the death of any form of living matter, at a given temperature, depends on the destruction of its fundamental substance at that heat, and how far death is brought about by the coagulation of merely accessory compounds.
Aniline and similar bases are oxidized and partially nitrated by nitroglycerin, with the production of non-explosive compounds.
Another question to which he gave much attention was the connexion of the boiling-point of compounds, organic ones in particular, with their composition.
Antimonial, bismuth and arsenical compounds were assiduously studied, a direct consequence of their high medicinal importance; mercurial and silver compounds were investigated for the same reason.
Aromatic Nitro Compounds.-The aromatic nitro compounds are generally obtained by the direct action of nitric acid.
As a general rule, compounds formed tive with a great evolution of heat have high boiling-points, and vice versa.
As an example another series of organic compounds may be taken, viz.
As before, only true ring nuclei, and not internal anhydrides of aliphatic compounds, will be mentioned.
As in other languages the verb " to be " and its compounds are irregular; the number of other irregular verbs is comparatively small.
As some of these sulphur compounds have a poisonous effect on plants, gas-lime cannot be applied to land directly without great risk or rendering it incapable of growing crops of any sort - even weeds - for some time.
At one time it was thought that these mixtures of constant boiling-point (an extended list is given in Young's Fractional Distillation) were definite compounds.
At the same time he clarified the conception of elements and compounds, rejecting the older notions, the four elements of the " vulgar Peripateticks " and the three principles of the " vulgar Stagyrists," and defining an element as a substance incapable of decomposition, and a compound as composed of two or more elements.
At the same time, however, he adhered to the classification of Lemery; and it was only when identical compounds were obtained from both vegetable and animal sources that this subdivision was discarded, and the classes were assimilated in the division organic chemistry.
At the same time, however, it forms a number of compounds in which it is most decidedly tetravalent; and thus it shows relations to carbon, silicon, germanium and tin.
At the same time, the diffusion of these compounds into contact with the cathode leads to a partial reduction to chloride, by the removal of combined oxygen by the instrumentality of the hydrogen there evolved.
At this time there existed a belief, held at a later date by Berzelius, Gmelin and many others, that the formation of organic compounds was conditioned by a so-called vital force; and the difficulty of artificially realizing this action explained the supposed impossibility of synthesizing organic compounds.
Atomic refractions may be obtained either directly, by investigating the various elements, or indirectly, by considering differences in the molecular refractions of related compounds.
Auric chloride combines with the hydrochlorides of many organic bases - amines, alkaloids, &c. - to form characteristic compounds.
Azoxy Compounds, R N O N R', are usually yellow or red crystalline solids which result from the reduction of nitro or nitroso compounds by heating them with alcoholic potash (preferably using methyl alcohol).
B aeyer has suggested that his hypothesis may also be applied to explain the instability of acetylene and its derivatives, and the still greater instability of the polyacetylene compounds.
Baeyer pointed out that although benzene derivatives were obtainable from hexamethylene compounds, yet it by no means follows that only hexamethylene compounds need result when benzene compounds are reduced.
Before the application of electricity, only two compounds were found suitable for reduction to the metallic state.
Benzene is of exceptional importance commercially on account of the many compounds derivable from it, which are exceedingly valuable in the arts.
Benzo-ortho-diazines exist in two structural forms, cinnolin and phthalazine; benzo-meta-diazines are known as quinazolines; benzo-para-diazines are termed quinoxalines; the dibenzo-compounds are named phenazines, this last group including many valuable dyestuffs - indulines, safranines, &c. In addition to the types of compounds enumerated above we may also notice purin, tropine and the terpenes.
Beryllium compounds are almost wholly prepared from beryl.
Berzelius, in 1813 and 1814, by improved methods of analysis, established that the Daltonian laws of combination held in both the inorganic and organic kingdoms; and he adopted the view of Lavoisier that organic compounds were oxides of compound radicals, and therefore necessarily contained at least three elements - carbon, hydrogen and oxygen.
Besides the buildings, the compounds include wide stretches of veld.
Beyond the small fertile valley in which it stands is the barren desert, on which rain rarely falls and which has no economic value apart from its minerals (especially saline compounds).
Bismuth forms compounds similar to the trisulphide with the elements selenium and tellurium.
Blagden (Ber.,1900,33,p.2544), who consider that three simultaneous reactions occur, namely, the formation of labile double salts which decompose in such a fashion that the radical attached to the copper atom wanders to the aromatic nucleus; a catalytic action, in which nitrogen is eliminated and the acid radical attaches itself to the aromatic nucleus; and finally, the formation of azo compounds.
Both these compounds afford delicate, unobtrusive and effective grounds for inlaying with gold, silver and other metals, as well as for sculpture, whether incised or in relief.
Buff carried out an inquiry on the compounds of silicon in which they prepared the previously unknown gas, silicon hydride or silicuretted hydrogen.
Busch (Ber., 1905, 38, pp. 856, 4049) has isolated a series of bridged ring compounds which he describes as endo-iminodihydrotriazoles, the triphenyl derivative (annexed formula) being prepared by condensing triphenylaminoguanidine with formic acid.
But the hydroxide of thallium, in most of its properties, comes very close to the alkali metals; it is strongly basic, forms an insoluble chloroplatinate, and an alum strikingly similar to the corresponding potassium compounds.
But the occasional or indeed frequent existence of chemical compounds in alloys has now been placed beyond doubt.
By oxidizing agents they are converted into azoxy compounds, and by reducing agents into hydrazo compounds or amines.
By reduction, the double linkages become saturated, and compounds result which stand in much about the same relation to the original nucleus as hexamethylene does to benzene.
By the condensation of ortho-aminophenols with phosgene or thiophosgene, oxy and thio-derivatives are obtained, the (OH) and (SH) groups being situated in the t t position, and these compounds on treatment with amines yield amino derivatives.
By transformations of the carbonyl group, and at the same time of the hydroxyl group, many interesting types of nitrogen compounds may be correlated.
By using urea, guanidine, thiourea and related compounds instead of amidines, one obtains the uracils.
Caesium compounds can be readily recognized by the two bright.
Caoutchouc, like other "unsaturated" molecules, forms compounds with chlorine, bromine, iodine and sulphur.
Cements of the Portland type differ in kind from those of the pozzuolanic class; they are not mechanical mixtures of lime and active silica ready to unite under suitable conditions, but consist of definite chemical compounds of lime and silica and lime and alumina, which, when mixed with water, combine therewith, forming crystalline substances of great mechanical strength, and capable of adhering firmly to clean inert material, such as stone and sand.
Cerium compounds may be recognized by the red precipitate of ceric hydroxide, which is formed when sodium hypochlorite is added to a colourless cerous salt.
Certain compounds withstand ring decomposition much more strongly than others; for instance,.
Changes of the first and second kind, according to our views of the constitution of molecules, are probably of very rare occurrence; in fact, chemical action appears almost always to involve the occurrence of both these kinds of change, for, as already pointed out, we must assume that the molecules of hydrogen, oxygen and several other elements are diatomic, or that they consist of two atoms. Indeed, it appears probable that with few exceptions the elements are all compounds of similar atoms united together by one or more units of affinity, according to their valencies.
Chemically it is one of the most interesting substances known, since it is the parent of the enormous number of compounds styled the " aromatic " or " benzenoid " compounds.
Chlorine and oxygen do not combine directly, but compounds can be obtained indirectly.
Chromium forms three series of compounds, namely the chromous salts corresponding to CrO, chromous oxide, chromic salts, corresponding to Cr203, chromium sesquioxide, and the chromates corresponding to Cr0,, chromium trioxide or chromic anhydride.
Claisen by condensing ethoxymethylene aceto-acetic esters and similar compounds with /3-ketonic esters and with 1.3 diketones.
Cleve, the first to make a really thorough study of these elements and their compounds.
Colour and Constitution.-In this article a summary of the theories which have been promoted in order to connect the colour of organic compounds with their constitution will be given, and the reader is referred to the article Colour for the physical explanation of this property, and to Vision for the physiological and psychological bearings.
Columbium compounds are usually prepared by fusing columbite with an excess of acid potassium sulphate, boiling out the fused mass with much water, and removing tin and tungsten from the residue by digestion with ammonium sulphide, any iron present being simultaneously converted into ferrous sulphide.
Columbus is near the Ohio coal and iron-fields, and has an extensive trade in coal, but its largest industrial interests are in manufactures, among which the more important are foundry and machine-shop products (1905 value, $6,259,579); boots and shoes (1905 value, $5,425,087, being more than one-sixtieth of the total product value of the boot and shoe industry in the United States, and being an increase from $359,000 in 1890); patent medicines and compounds (1905 value, $3,214,096); carriages and wagons (1905 value, $2,197,960); malt liquors (1905 value, $2,133,955); iron and steel; regalia and society emblems; steam-railway cars, construction and repairing; and oleo-margarine.
Commercially, barytes is used in the preparation of barium compounds, as a body for certain kinds of paper and cloth, and as a white pigment ("permanent white").
Compounds are known which may be looked upon as derived from ammonia by the replacement of its hydrogen by the sulpho-group (HS0 3); thus potassium ammon-trisulphonate,N(SO 3 K) 3.2H20,is obtained as a crystalline precipitate on the addition of excess of potassium sulphite to a solution of potassium nitrite, KN02+3K2S03+2H20=N(S03K) 3 +4KHO.
Compounds generally show spectra of resolvable bands, and if an elementary body shows a spectrum of the same type we are probably justified in assuming it to be due to a complex molecule.
Compounds in which all the units of affinity of the contained elements are engaged are said to be saturated, whilst those in which the affinities of the contained elements are not all engaged by other elements are said to be unsaturated.
Compounds of Copper.-Copper probably forms six oxides, viz.
Compounds of fluorine and oxygen, and of bromine and oxygen, have not yet been isolated.
Compounds were denoted by joining the symbols of the components, and by varying the manner of joining compounds of the same elements were distinguished The symbol V was used to denote a liquid, and a vertical line to denote a gas.
Compounds were represented by copulating simpler symbols, e.g.
Concentrated acids convert them into the isomeric nitro-amines, the - NO 2 group going into the nucleus in the orthoor paraposition to the amine nitrogen; this appears to indicate that the compounds are nitramines.
Confining our attention, for the present, to di-substitution products we see that there are three distinct series of compounds to be considered.
Considering the predicted series of compounds C7,H2,,+2, which is the well-known homologous series of methane, the first member, the possible of isomerism lies in that of a different linking of the carbon atoms. This first presents itself when four are present, i.e.
Contaminated as it was with potassium and with platinum from the crucible, the metal formed a grey powder and was far from pure; but in 1845 he improved his process and succeeded in producing metallic globules wherewith he examined its chief properties, and prepared several compounds hitherto unknown.
Copper combines directly with phosphorus to form several compounds.
Crum was probably the first to recognize that some hydrogen atoms of the cellulose had been replaced by an oxide of nitrogen, and this view was supported more or less by other workers, especially Hadow, who appears to have distinctly recognized that at least three compounds were present, the most violently explosive of which constituted the main bulk of the product commonly obtained and known as guncotton.
Custom has to some extent restricted its use to inorganic chemistry; the corresponding property of organic compounds being generally termed isomerism.
Cyanogen compounds of chromium, analogous to those of iron, have been prepared; thus potassium chromocyanide, K 4 Cr(CN) 6.2H 2 0, is formed from potassium cyanide and chromous acetate; on exposure to air it is converted into the chromicyanide, K 3 Cr(CN) 6, which can also be prepared by adding chromic acetate solution to boiling potassium cyanide solution.
Deferring the detailed discussion of cyclic or ringed hydrocarbons, a correlation of the various types or classes of compounds which may be derived from hydrocarbon nuclei will now be given.
Detection and Estimation.-Most calcium compounds, especially when moistened with hydrochloric acid, impart an orange-red colour to a Bunsen flame, which when viewed through green glass appears to be finch-green; this distinguishes it in the presence of strontium, whose crimson coloration is apt to mask the orange-red calcium flame (when viewed through green glass the strontium flame appears to be a very faint yellow).
Double Nature of the Carbon-Iron Diagram.-The part played by graphite in the constitution of the iron-carbon compounds, hitherto ignored for simplicity, is shown in fig.
Dumas, who regarded them as hydrates of olefiant gas (ethylene); on the other they yielded chloroform, chloral and aldehyde, as well as other compounds of less general interest, and also the method of forming mirrors by depositing silver from a slightly ammoniacal solution by acet aldehyde.
During recent years an immense number of ringed or cyclic compounds have been discovered, which exhibit individual characters more closely resembling benzene, naphthalene, &c. than purely aliphatic substances, inasmuch as in general they contain double linkages, yet withstand oxidation, and behave as nuclei, forming derivatives in much the same way as benzene.
Edmond Becquerel was associated with his father in much of his work, but he himself paid special attention to the study of light, investigating the photochemical effects and spectroscopic characters of solar radiation and the electric light, and the phenomena of phosphorescence, particularly as displayed by the sulphides and by compounds of uranium.
Eltekow, Ber., 1878, 11, p. 414); by the action of metals on the halogen compounds Cn.H 20 Br 2 i by boiling the aqueous solution of nitrites of the primary amines (V.
Examination of the absorption spectra of coloured compounds shows that certain groupings displace the absorption bands in one direction, and other groupings in the other.
Experience has shown that such mono-derivatives as nitro compounds, sulphonic acids, carboxylic acids, aldehydes, and ketones yield as a general rule chiefly the meta-compounds, and this is independent of the nature of the second group introduced; on the other hand, benzene haloids, amino-, homologous-, and hydroxy-benzenes yield principally a mixture of the orthoand para-compounds.
Fischer showed that these compounds were derivatives of triphenylmethane and tolyldiphenylmethane respectively.
For example, compounds of oxygen are oxides, of chlorine, chlorides, and so on.
For other minerals, see Compounds of Copper below.
For purposes of substitution, the free element as a rule only works slowly on saturated compounds, but the reaction may be accelerated by the action of sunlight or on warming, or by using a "carrier."
For the carrying on of their functions they all need to be supplied with carbohydrates or other carbon compounds which they obtain ordinarily from humus and plant residues in the soil, or possibly in some instances from carbohydrates manufactured by minute green algae with which they live in close union.
For the preparation of pure cerium compounds see Auer v.
For the preparation of yttrium compounds the best raw material is gadolinite, which, according to Kiinig, consists of 22.61% of silica, 34.64.
Formerly the name was given to compounds having a sweet taste, e.g.
Fowler that these flutings are due to titanium oxide; this probably indicates a relatively low temperature, for at a high temperature all compounds would be dissociated.
Fraser proved that by substitution of molecules in certain compounds a stimulant could be converted into a sedative action; thus by the addition of the methyl group CH 2 to the molecule of strychnine, thebaine or brucine, the tetanizing action of these drugs is converted into a paralysing action.
From a detailed study of organic compounds Gerhardt had promulgated a " theory of types " which represented a fusion of the older radical and type theories.
From similar investigations of valerianic acid he was led to conclude that fatty acids were oxygen compounds of the radicals hydrogen, methyl, ethyl, &c., combined with the double carbon equivalent C2.
From the fact that reduction products containing either one or two double linkages behave exactly as unsaturated aliphatic compounds, being readily reduced or oxidized, and combining with the halogen elements and haloid acids, it seems probable that in benzenoid compounds the fourth valencies are symmetrically distributed in such a manner as to induce a peculiar stability in the molecule.
From the primary amines are derived the diazo compounds and azo compounds; closely related are the hydrazines (q.v.).
From these nuclei an immense number of derivatives may be obtained, for the hydrogen atoms may be substituted by any of the radicals discussed in the preceding section on the classification of organic compounds.
Further differences become apparent when various typical compounds are compared.
Gas-lime is a product obtained from gasworks where quicklime is used to purify the gas from sulphur compounds and other objectionable materials.
Germanium compounds on fusion with alkaline carbonates and sulphur form salts known as thiogermanates.
Grignard (Comptes rendus, 1900 et seq.) observed that magnesium and alkyl or aryl halides combined together in presence of anhydrous ether at ordinary R temperatures (with the appearance of brisk boiling) to form compounds of the type RMgX(R = an alkyl or aryl group and X = halogen).
Haemoglobin is composed of a basic albumin and an acid substance haematin; it combines readily with oxygen, carbon dioxide and carbon monoxide to form loose compounds.
Hantzsch (Ber., 18 99, 3 2, pp. 59 o, 3089) considers that the oxyazo compounds are to be classed as pseudoacids, possessing in the free condition the configuration of quinone hydrazones, their salts, however, being of the normal phenolic type.
Hantzsch (Ber., 1889, 22, p. 1238) succeeded in ob R taining derivatives of o-diketo-R-hexene, which yield R-pentene and aliphatic compounds on decomposition.
Hantzsch explains the characteristic reactions of the diazonium compounds ky the assumption that an addition compound is first formed, which breaks down with the elimination of the hydride of the acid radical, and the formation of an unstable syn-diazo compound, which, in its turn, decomposes with evolution of nitrogen (Ber., 18 97, 30, p. 2 54 8; 1898, 31, p. 2053).
Hantzsch, Ber., This assumption also shows the relationship of the diazonium hydroxides to other quaternary ammonium compounds, for most of the quaternary ammonium hydroxides (except such as have the nitrogen atom attached to four saturated hydrocarbon radicals) are unstable, and readily pass over into compounds in which the hydroxyl group is no longer attached to the amine nitrogen; thus the syn-diazo hydroxides are to be regarded as pseudo-diazonium derivatives.
He advanced towards the modern view of elements as the undecomposable constituents of material bodies; and understanding the distinction between mixtures and compounds, he made considerable progress in the technique of detecting their ingredients, a process which he designated by the term "analysis."
He also investigated the oxygen compounds of phosphorus and nitrogen, and was ' The names of the musical instruments in those verses of the Book of Daniel have formed the basis of a controversy as to the authenticity of the book.
He applied himself more particularly to the oxygen compounds, and determined with a fair degree of accuracy the ratio of carbon to oxygen in carbon dioxide, but his values for the ratio of hydrogen to oxygen in water, and of phosphorus to oxygen in phosphoric acid, are only approximate; he introduced no new methods either for the estimation or separation of the metals.
He assumed that if we have one atom 1 It is now established that ortho compounds do exist in isomeric forms, instances being provided by chlor-, brom-, and amino-toluene, chlorphenol, and chloraniline; but arguments, e.g.
He held the doctrine that the chemical elements are compounds of equal and similar atoms, and might therefore possibly be all derived from one generic atom.
He is known for a long series of researches on the constitution of alkaloids and of the albuminoid bodies, and for the preparation of several new series of platinum compounds and of hyposulphurous acid, H 2 S 2 O 4.
He realized that the composition by weight of chemical compounds was of the greatest moment if chemistry were to advance.
He regarded the chemical properties of a substance as due to (1) the chemical atoms composing it, and (2) the structure, and he asserted that while different compounds might have the same components (isomerism), yet only one compound could have a particular structure.
He rejected the Berzelian tenet as to the unalterability of radicals, and admitted that they exercised a considerable influence upon the compounds with which they were copulated.
He suggests that the term " quinone " theory be abandoned, and replaced by the Umlagerungs theory, since this term implies some intermolecular rearrangement, and does not connote simply benzenoid compounds as does " quinonoid."
He was thus enabled to predict compounds which were then unknown.
Here compounds of divalent lead have not yet been obtained; by acting with zinc ethide on lead chloride, lead tetraethide, Pb(C 2 IH Q) 4, is obtained, with the separation of metallic lead.
Here we shall only discuss the structure of these compounds in the light of the modern benzene theories; reference should be made to the articles Naphthalene, Anthracene and Phenanthrene for syntheses, decompositions, &c.
His analytical skill enabled him to demonstrate the inaccuracy of the researches by which Berthollet attempted to support the opposite view, and to show among other things that some of the compounds which Berthollet treated as oxides were in reality hydrates containing chemically combined water, and the upshot was that by 1808 he had fully vindicated his position.
His contributions to inorganic chemistry were numerous, including investigations on the compounds of antimony, aluminium, silicon, &c., on the separation of nickel and cobalt, and on the analysis of mineral waters, but they are outweighed in importance by his work on organic substances.
His first original paper (1799) was on the compounds of arsenic and antimony with oxygen and sulphur, and of his other separate investigations one of the most important was that on the compound ethers, begun in 1807.
His most important achievement was to define "salts" - a term formerly used in the most loose and indeterminate way - as the compounds formed by the union of acids and bases, and further to distinguish between neutral, basic and acid salts.
Hitherto we have generally restricted ourselves to syntheses which result in the production of a true benzene ring; but there are many reactions by which reduced benzene rings are synthesized, and from the compounds so obtained true benzenoid compounds may be prepared.
However, in 1833, Berzelius reverted to his earlier opinion that oxygenated radicals were incompatible with his electrochemical theory; he regarded benzoyl as an oxide of the radical C 14 H 1Q, which he named " picramyl " (from 7rucp6s, bitter, and &uvyalk, almond), the peroxide being anhydrous benzoic acid; and he dismissed the views of Gay Lussac and Dumas that ethylene was the radical of ether, alcohol and ethyl chloride, setting up in their place the idea that ether was a suboxide of ethyl, (C2H5)20, which was analogous to K 2 0, while alcohol was an oxide of a radical C 2 H 6; thus annihilating any relation between these two compounds.
Huntingdon examined by photographic methods the absorption spectra of a great number of organic compounds.
Hydrocarbons containing any number of double or triple linkages, as well as both double and triple linkages, are possible, and a considerable number of such compounds have been prepared.
Hydrogen and oxygen are, therefore, of very opposite natures, and this is well illustrated by the circumstance that oxygen combines, with very few exceptions, with all the remaining elements, whilst compounds of only a limited number with hydrogen have been obtained.
Hydrogen combines with oxygen to form two definite compounds, namely, water (q.v.), H 2 O, and hydrogen peroxide, H202, whilst the existence of a third oxide, ozonic acid, has been indicated.
Hydrogen, as was shown by Graham, is capable of uniting with or being occluded by certain metals, notably with palladium (q.v.), into metal-like compounds.
Identity in composition, but difference in constitution, is generally known as " isomerism " (q.v.), and compounds satisfying this relation differ in many of their physical properties.
If a-naphthylamine and a-naphthol be reduced, the hydrogen atoms attach themselves to the non-substituted half of the molecule, and the compounds so obtained resemble aminodiethylbenzene, C 6 H 3 NH 2 (C 2 H 5) 21 and oxydiethylbenzene, C 6 H 3.
If forms two series of salts, one, the uranous compounds, are derived from the oxide U02, the other, the uranyl compounds, contain the divalent group U02.
If this is admitted the poverty of tropical sea-water in mineral nitrogen compounds is explained by the higher temperature, which accelerates the activity of denitrifying bacteria.
If two compounds combined, the + signs of the free compounds were discarded, and the number of atoms denoted by an Arabic index placed after the elements, and from these modified symbols the symbol of the new compound was derived in the same manner as simple compounds were built up from their elements.
If we accept Kekule's formula for the benzene nucleus, then we may expect the double linkages to be opened up partially, either by oxidation or reduction, with the formation of di-, tetra-, or hexa-hydro derivatives, or entirely, with the production of open chain compounds.
In 1799 he proved that carbonate of copper, whether natural or artificial, always has the same composition, and later he showed that the two oxides of tin and the two sulphides of iron always contain the same relative weights of their components and that no intermediate indeterminate compounds exist.
In 1832 he published, jointly with Willer, one of the most famous papers in the history of chemistry, that on the oil of bitter almonds (benzaldehyde), wherein it was shown that the radicle benzoyl might be regarded as forming an unchanging constituent of a long series of compounds obtained from oil of bitter almonds, throughout which it behaved like an element.
In a note published in 18 r.1 he described the physical properties of this acid, but he said nothing about its chemical composition till 1815, when he described cyanogen as a compound radicle, prussic acid as a compound of that radicle with hydrogen alone, and the prussiates (cyanides) as compounds of the radicle with, metals.
In a scientific definition the compounds of fatty acids with basic metallic oxides, lime, magnesia, lead oxide, &c., should also be included under soap; but, as these compounds are insoluble in water, while the very essence of a soap in its industrial relations is solubility, it is better to speak of the insoluble compounds as " plasters, " limiting the name " soap " as the compounds of fatty acids with soda and potash.
In acid solution, amines are obtained, in alkaline solution, azoxy, azo and hydrazo compounds, and in neutral solution hydroxylamino compounds.
In addition to the above series there are a considerable number of compounds derived from purin which are by some writers classed with the alkaloids.
In addition to the vitalistic doctrine of the origin of organic compounds, views based on purely chemical considerations were advanced.
In connexion with these experiments he developed the electric furnace as a convenient means of obtaining very high temperatures in the laboratory; and by its aid he prepared many new compounds, especially carbides, silicides and borides, and melted and volatilized substances which had previously been regarded as infusible.
In France this slaking is conducted systematically by the makers, the freshly burned lime being sprinkled with water and stored in large bins where slaking proceeds slowly and regularly until the whole of the surplus uncom bined lime is slaked and rendered harmless, while the cementitious compounds, notably tricalcium silicate, remain untouched.
In general it is pentavalent, but divalent compounds are known.
In general these compounds are decomposable by heat, but some of them, such as those of gold, silver, copper and the alkali metals, even when heated above the boiling point of mercury retain mercury and leave residues of definite composition.
In general, the aliphatic residues in such mixed compounds retain the characters of their class, while the aromatic residues retain the properties of benzene.
In general, therefore, it may be considered that the double linkages are not of exactly the same nature as the double linkage present in ethylene and ethylenoid compounds, but that they are analogous to the potential valencies of benzene.
In his researches on the bleaching compounds of chlorine he was the first to advance the view that bleaching-powder is a double compound of calcium chloride and hypochlorite; and he devoted much time to the problem of economically obtaining soda and potash from seawater, though here his efforts were nullified by the discovery of the much richer sources of supply afforded by the Stassfurt deposits.
In modern chemistry alkali is a general term used for compounds which have the property of neutralizing acids, and is applied more particularly to the highly soluble hydrates of sodium and potassium and of the three rarer "alkali metals," caesium, rubidium and lithium, also to aqueous ammonia.
In regard to the ancients' knowledge of lead compounds, we may state that the substance described by Dioscorides as, uoXv,3Saiva was undoubtedly litharge, that Pliny uses the word minium in its present sense of red lead, ana that white lead was well known to Geber in the 8th century.
In some cases definite compounds have been isolated from amalgams which may be regarded as mixtures of one or more of such compounds with mercury in excess.
In the article Thermo Chemistry a general account of heats of formation of chemical compounds is given, and it is there shown that this constant measures the stability of the compound.
In the case of tetra-substituted compounds, thirty isomers are possible when all the groups are different.
In the case of the ferromagnetic metals and some of their alloys and compounds, the permeability has generally a much higher value.
In the case of two substances which neither form compounds nor dissolve each other in the solid state, the complete freezing-point curve takes the form shown infig.5.
In the first place we may notice a tendency of several aliphatic compounds, e.g.
In the first stage the ammonium compounds are oxidized to nitrites by the agency of very minute motile bacteria belonging to the genus Nitrosomonas.
In the former he was one of the leading workers, in collaboration from 1879 to 1887 with Emile Edmond Sarasin (1843-1890), at the formation of minerals by artificial means, particularly in the wet way with the aid of heat and pressure, and he succeeded in reproducing a large number of the natural compounds.
In the Fungi it is usually composed of a modified form of cellulose known as fungus cellulose, which, according to Mangin, consists of callose in combination either with cellulose or pectic compounds.
In the generation of acetylene from calcium carbide and water, all that has to be done is to bring these two compounds into contact, when they mutually react upon each other with the formation of lime and acetylene, while, if there be sufficient water present, the lime combines with it to form calcium hydrate.
In the same year Berzelius discovered selenium in a deposit from sulphuric acid chambers, his masterly investigation including a study of the hydride, oxides and other compounds.
In the second group, we may notice the application of litmus, methyl orange or phenolphthalein in alkalimetry, when the acid or alkaline character of the solution commands the colour which it exhibits; starch paste, which forms a blue compound with free iodine in iodometry; potassium chromate, which forms red silver chromate after all the hydrochloric acid is precipitated in solutions of chlorides; and in the estimation of ferric compounds by potassium bichromate, the indicator, potassium ferricyanide, is placed in drops on a porcelain plate, and the end of the reaction is shown by the absence of a blue coloration when a drop of the test solution is brought into contact with it.
In the separation of the constituents of the complex mixture of oxides obtained from the " rare earth " minerals, the methods generally forced upon chemists are those of fractional precipitation or crystallization; the striking resemblances of the compounds of these elements rarely admitting of a complete separation by simple precipitation and filtration.
In the thallous series many analogies with lead compounds are observed; in the thallic some resemblance to aluminium and gold.
In the vegetable kingdom glucose occurs, always in admixture with fructose, in many fruits, especially grapes, cherries, bananas, &c.; and in combination, generally with phenols and aldehydes belonging to the aromatic series, it forms an extensive class of compounds termed glucosides.
In these solid solutions, as in aqueous ones, the ratios in which the different chemical substances are present are not fixed or definite, but vary from case to case, not per saltum as between definite chemical compounds, but by infinitesimal steps.
In this, as in most other cases in which substances act upon one another under such circumstances that the resulting compounds are free to react, the extent to which the different kinds of action which may occur take place is dependent upon the mass of the substances present in the mixture.
Incidentally in 1777 Scheele prepared sulphuretted hydrogen, and noted the chemical action of light on silver compounds and other substances.
Inorganic Chemistry Inorganic chemistry is concerned with the descriptive study o f the elements and their compounds, except those of carbon.
Intermolecular transformations-migrations of substituent groups from one carbon atom to anotherare of fairly common occurrence among oxy compounds at elevated temperatures.
Iodine finds application in organic chemistry, forming addition products with unsaturated compounds, the combination, however, being more slow than in the case of chlorine or bromine.
It abolished the conception of life s an entity above and beyond the common properties of matter, and led to the conviction that the marvellous and exceptional qualities of that which we call " living " matter are nothing more nor less than an exceptionally complicated development of those chemical and physical properties which we recognize in a gradually ascending scale of evolution in the carbon compounds, containing nitrogen as well as oxygen, sulphur and hydrogen as constituent atoms of their enormous molecules.
It also finds an extensive use in organic chemistry as a substituting and oxidizing agent, as well as for the preparation of addition compounds.
It combines directly with many elements and compounds and frequently acts as energetic oxidizing agent.
It combines with aromatic amines to form azocompounds, with arylhydroxylamines to form azoxy compounds, and with hydroxylamine it gives isodiazobenzene.
It combines with gaseous ammonia and forms crystalline compounds with certain alcohols.
It consists essentially of cinnamic aldehyde, and by the absorption of oxygen as it becomes old it darkens in colour and develops resinous compounds.
It dissolves most organic compounds, resins, hydrocarbons, fatty acids and many metallic salts, sometimes forming, in the latter case, crystalline compounds in which the ethyl alcohol plays a role similar to that of water of crystallization.
It exhibits itself in the peculiar behaviour of some organic compounds containing the group - C CO.
It forms addition compounds similar to those formed by stannic chloride, and combines with ammonia to form TiCl 4.8NH 3 and TiC1 4.6NH 3, both of which with liquid ammonia give titanamide, Ti(NH2)4.
It forms addition compounds with unsaturated compounds.
It forms crystalline compounds with ammonia and the organic bases.
It forms crystalline compounds with bromine and with many metallic salts.
It forms double salts such as MgTh(NO 3) 6.8H 2 O, which are isomorphous with the corresponding cerium compounds.
It is a powerful reducing agent, and is frequently employed for this purpose in organic chemistry; thus hydroxy acids are readily reduced on heating with the concentrated acid, and nitro compounds are reduced to amino compounds, &c. It is preferable to use the acid in the presence of amorphous phosphorus, for the iodine liberated during the reduction is then utilized in forming more hydriodic acid, and consequently the original amount of acid goes much further.
It is also formed in ordinary fermentation processes, in the combustion of all carbon compounds (oil, gas, candles, coal, &c.), and in the process of respiration.
It is convenient to treat these glasses as " normal " glasses, but they are in reality mixtures of silicates, and cannot rightly be regarded as definite chemical compounds or represented by definite chemical formulae.
It is decomposed by heat into oxide, nitrogen peroxide and oxygen; and is used for the manufacture of fusees and other deflagrating compounds, and also for preparing mordants in the dyeing and calico-printing industries.
It is excreted when many aromatic compounds, such as benzoic acid and toluene, are taken internally.
It is found that most organic compounds containing the grouping CH 3 CO.
It is found that transparent oils under the influence of light absorb oxygen, becoming deeper in colour and opalescent, while strong acidity and a penetrating odour are developed, these changes being due to the formation of various acid and phenylated compounds, which are also occasionally found in fresh oils.
It is found, more especially in the case of organic compounds, that if a substance which oxidizes readily at ordinary temperature be mixed with another which is not capable of such oxidation, then both are oxidized simultaneously, the amount of oxygen used being shared equally between them; or in some cases when the substance is spontaneously oxidized an equivalent amount of oxygen is converted into ozone or hydrogen peroxide.
It is invariably present in soils, where compounds are formed by nitrifying bacteria.
It is necessary clearly to distinguish such compounds as the amino- (or amido-) acids and acid-amides; in the first case the amino group is substituted in the hydrocarbon residue, in the second it is substituted in the carboxyl group.
It is necessary, therefore, to avoid reactions involving such intermolecular migrations when determining the orientation of aromatic compounds.
It is often convenient to regard compounds as formed upon certain types; alcohol, for example, may be said to be a compound formed upon the water type, that is to say, a compound formed from water by displacing one of the atoms of hydrogen by the group of elements C 2 H 5, thus - H C2H5 O H O H Water Alcohol.
It is probable that the whole phenomenon of isomerism is due to the possibility that compounds or systems which in reality are unstable yet persist, or so slowly change that practically one can speak of their stability; for instance, such systems as explosives and a mixture of hydrogen and oxygen, where the stable form is water, and in which, according to some, a slow but until now undetected change takes place even at ordinary temperatures.
It is remarkable that a great many polymorphous substances assume more symmetrical forms at higher temperatures, and a possible explanation of the increase in density of such compounds as silver iodide, &c., may be sought for in the theory that the formation of a more symmetrical configuration would involve a drawing together of the molecules, and consequently an increase in density.
It is remarkable that sulphur can replace two methine or CH groups with the production of compounds greatly resembling the original one.
It is thus seen that the ordinary plane representation of the structure of compounds possesses a higher significance than could have been suggested prior to crystallographical researches.
It is true that by the distillation of many herbs, resins and similar substances, several organic compounds had been prepared, and in a few cases employed as medicines; but the prevailing classification of substances by physical and; superficial properties led to the correlation of organic and inorganic compounds, without any attention being paid to their chemical composition.
It is unnecessary here to dwell on the precautions which can only be conveniently acquired by experience; a sound appreciation of analytical methods is only possible after the reactions and characters of individual substances have been studied, and we therefore refer the reader to the articles on the particular elements and compounds for more information on this subject.
It is, however, a useful superficial caustic and antiseptic. All copper compounds are poisonous, but not so harmful as the copper arsenical pigments.
It may be noted that all thallium compounds are poisonous.
It oxidizes carbon compounds to carbon dioxide and water, and therefore finds extensive application in analytical organic chemistry.
It reacts most energetically with many organic compounds, removing the elements of water in many cases and leaving a carbonized mass.
It reacts with carbonyl compounds, giving semi-carbazones, and in consequence is frequently used for characterizing such substances.
It therefore appears that the difference between the heats of combustion of two adjacent members of a series of homologous compounds is practically a constant, and that this constant has two average values, viz.
It was based on an accidental observation of the action of metallic aluminium on amyl chloride, and consists in bringing together a hydrocarbon and an organic chloride in presence of aluminium chloride, when the residues of the two compounds unite to form a more complex body.
It was soon found, however, that compounds possess their own characteristic spectra, and that an element may give under special conditions of luminosity several different spectra.
It will be noticed that compounds containing two double linkages will have the same general formula as the acetylene series; such compounds are known as the " diolefines."
It would seem that, on the whole, nitrogen compounds in the ocean (whether existing in the organic or inorganic forms) remain constant in amount.
Its value as a dyestuff depends on its power of forming insoluble compounds (lakes) with metallic oxides.
Jager in complicated organic compounds.
Kekule's main importance lies in the far-reaching contributions which he made to chemical theory, especially in regard to the constitution of the carbon compounds.
Kolbe had an important share in the great development of chemical theory that occurred about the middle of the 19th century, especially in regard to the constitution of organic compounds, which he viewed as derivatives of inorganic ones, formed from the latter - in some cases directly - by simple processes of substitution.
Kolbe was a very successful teacher, a ready and vigorous writer, and a brilliant experimentalist whose work revealed the nature of many compounds the composition of which had not previously been understood.
Kopp, begun in 1842, on the molecular volumes, the volume occupied by one gramme molecular weight of a substance, of liquids measured at their boiling-point under atmospheric pressure, brought to light a series of additive relations which, in the case of carbon compounds, render it possible to predict, in some measure, the cornposition of the substance.
Later the nitrogen-content of the nodule decreases, most of the organisms, which are largely composed of proteid material, becoming digested and transformed into soluble nitrogenous compounds which are conducted to the developing roots and seeds.
Leber experimented with several chemical compounds to find what reaction they had on these cells; by using fine glass tubes sealed at the outer end and containing a chemical substance, and by introducing the open end into the blood vessels he found that the leucocytes were attracted - positive chemiotaxis - by the various compounds of mercury, copper, turpentin, and other substances.
Let us suppose that a molten mixture of two substances A and B, which at a sufficiently high temperature form a uniform liquid, and which do not combine to form definite compounds, is slowly cooled until it becomes wholly solid.
Long-continued treatment with halogens may, in some cases, result in the formation of aromatic compounds; thus perchlorbenzene, C 6 C1 6, frequently appears as a product of exhaustive chlorination, while hexyl iodide, C 6 H 13 I, yields perchlorand perbrom-benzene quite readily.
Lowry and Armstrong represent these compounds by the following spatial formulae which postulate a y-oxidic structure, and 5 asymmetric carbon atoms, i.e.
Many compounds containing hydrogen are readily decomposed by the gas; for example, a piece of paper dipped in turpentine inflames in an atmosphere of chlorine, producing hydrochloric acid and a copious deposit of soot; a lighted taper burns in chlorine with a dull smoky flame.
Many instances have been recorded where substitution has effected a deformation in one particular direction, the crystals of homologous compounds often exhibiting the same angles between faces situated in certain zones.
Many of their compounds are very strongly magnetic, erbium, for example, in Er203 being four times as strong as iron in the familiar magnetite or lodestone, Fe203.
Many other inter-metallic compounds have been indicated by summits in freezing-point curves.
Marine Gasteropods are occasionally termed "sea-snails," and the compounds "pond-snails," "river-snails," "water-snails" are in common use.
Matthiessen in 1855, who obtained the metal by electrolysis and thoroughly examined it and its compounds.
Mendeleeff also devoted much study to the nature of such "indefinite" compounds as solutions, which he looked upon as homogeneous liquid systems of unstable dissociating compounds of the solvent with the substance dissolved, holding the opinion that they are merely an instance of ordinary definite or atomic compounds, subject to Dalton's laws.
Messinger, and we may hope that with subsequent improvements it may be adapted to all classes of organic compounds.
Meyer (Ber., 18 94, 2 7, p. 510 et seq.) showed that in benzenoid compounds ortho-substituents exert a great hindering effect on the esterification of alcohols by acids in the presence of hydrochloric acid, this hindering being particularly marked when two substituents are present in the ortho positions to the carboxyl group. In such a case the ester is best prepared by the action of an alkyl halide on the silver salt of the acid, and when once prepared, can only be hydrolysed with great difficulty.
Meyer formulated these compounds as nitroximes or nitro-isnitroso derivatives, viz.
Meyer, which are formed when nitrous acid acts on primary aliphatic nitro compounds.
Microscopic examination fully confirms the existence of these compounds.
Mineral nitrogenous compounds (nitrates, nitrites and ammonia) are much more rare.
Mixed aromatic-aliphatic amines, both secondary and tertiary, are also more strongly basic than the pure aromatic amines, and less basic than the true aliphatic compounds; e.g.
Molybdenum combines with the halogen elements in varying proportions, forming with chlorine a di-, tri-, tetraand penta-chloride, and similar compounds with bromine and iodine.
Most of the polynitro compounds are not volatile, but undergo deco Imposition on heating.
Mourlot has shown that aluminium sulphide, zinc sulphide and cadmium sulphide are the only sulphur compounds which can resist the heat of the electric furnace without decomposition or volatilization, and of these aluminium sulphide is the only one which is decomposed by water with the evolution of sulphuretted hydrogen.
Nature has provided several species of animals, birds and reptiles, to feed upon these insects, and various poisonous and suffocating compounds are used to destroy them, but with no great degree of success.
Neither of the above rules can be applied to carbon compounds containing nitrogen.
Neumann, who, in 1831, deduced from observations on many carbonates (calcium, magnesium, ferrous, zinc, barium and lead) that stoichiometric quantities (equimolecular weights) of compounds possess the same heat capacity.
Nilson, and subsequently (1904) by Hall, rendered notable additions to our knowledge of these elements and their compounds.
Nitrosohydrocarbons have been prepared in the aliphatic series by the oxidation of the corresponding hydroxylamino compounds.
No Doubt There Must Be Approximate Relations Between The Atomic And Molecular Heats Of Similar Elements And Compounds, But Considering The Great Variations Of Specific Heat With Temperature And Physical State, In Alloys, Mixtures Or Solutions, And In Allotropic Or Other Modifications, It Would Be Idle To Expect That The Specific Heat Of A Compound Could Be Accurately Deduced By Any Simple Additive Process From That Of Its Constituents.
Now in oxidizing, or introducing more oxygen, for instance, by means of a mixture of sulphuric acid and potassium bichromate, and admitting that oxygen acts on both compounds in analogous ways, the two alcohols may give (as they lose two atoms of hydrogen) CH 3 CH 2 COH and CH 3 C0 CH 3.
Now, in this case, the first definition expresses much better the whole chemical behaviour of ozone, which is that of "energetic" oxygen, while the second only includes the fact of higher vapour-density; but in applying the first definition to organic compounds and calling isobutylene "butylene with somewhat more energy" hardly anything is indicated, and all the advantages of the atomic conception - the possibility of exactly predicting how many isomers a given formula includes and how you may get them - are lost.
Numerous nitroso compounds are met with in the aromatic series.
Of recent years the introduction of various organic compounds as precipitants or reagents has reduced the labour of the process; and advantage has also been taken of the fairly complex double salts which these metals form with compounds.
Of the aromatic compounds azo-benzene is bright orange-red, and a-azonaphthalene forms red needles or small steel-blue prisms. The azogroup, however, has little or no colouring effect when present in a ring system, such as in cinnolene, phthalazine and tolazone.
Of the halogen compounds of phosphorus, the trichloride was discovered by Gay Lussac and Thenard, while the pentachloride was obtained by Davy.
Of the nitrogenous compounds in food, on the other hand, only a small proportion of the whole consumed is finally stored up in the increase of the animal - in other words, a very large amount of nitrogen passes through the body beyond that which is finally retained in the increase, and so remains for manure.
On account of the readiness with which it condenses with various compounds, benzaldehyde is an important synthetic reagent.
On the basis of the relation between physical phenomena and thermodynamical laws, properties of the polymorphous compounds may be predicted.
On the other hand the stability of the known oxygen compounds increases with the atomic weight, thus iodine pentoxide is, at ordinary temperatures, a well-defined crystalline solid, which is only decomposed on heating strongly, whilst chlorine monoxide, chlorine peroxide, and chlorine heptoxide are very unstable, even at ordinary temperatures, decomposing at the slightest shock.
Ores in which the copper is present as oxide or carbonate are soluble in sulphuric or hydrochloric acids, ferrous chloride, ferric sulphate, ammoniacal compounds and sodium thiosulphate.
Organic Chemistry While inorganic chemistry was primarily developed through the study of minerals - a connexion still shown by the French appellation chimie minerale - organic chemistry owes its origin to the investigation of substances occurring in the vegetable and animal organisms. The quest of the alchemists for the philosopher's stone, and the almost general adherence of the iatrochemists to the study of the medicinal characters and preparation of metallic compounds, stultified in some measure the investigation of vegetable and animal products.
Organic compounds are rapidly attacked by the gas.
Organo-metallic compounds can also be prepared, for example SnBr 4 +4MgBrC 6 H 5 =4MgBr2+Sn(C6H5) 4.
Orientation of Substituent Groups.-The determination of the relative positions of the substituents in a benzene derivative constitutes an important factor in the general investigation of such compounds.
Other lead compounds give the same black coloration from the formation of sulphide.
P. Laurie has determined the electromotive force of a series of copper-zinc, copper-tin and gold-tin alloys, and as the result of his experiments he points to the existence of definite compounds.
Perceiving a molecular isonomy between them and the inorganic compounds of the metals from which they may be formed, he saw their true molecular type in the oxygen, sulphur or chlorine compounds of those metals, from which he held them to be derived by the substitution of an organic group for the oxygen, sulphur, &c. In this way they enabled him to overthrow the theory of conjugate compounds, and they further led him in 1852 to publish the conception that the atoms of each elementary substance have a definite saturation capacity, so that they can only combine with a certain limited number of the atoms of other elements.
Perhaps the most remarkable discovery of modern chemistry is the existence of compounds, which, whilst possessing an identical composition, are absolutely different bodies, judged of by their properties.
Pharmacology And Therapeutics Of Zinc Compounds Zinc chloride is a powerful caustic, and is prepared with plaster of Paris in the form of sticks for destroying warts, &c. Its use for this purpose at the present day is, however, very rare, the knife or galvanocautery being preferred in most cases.
Polymethylenes can give only secondary and tertiary alcohols, benzene only tertiary; these latter compounds are known as phenols.
Practically the metals iron, nickel and cobalt, and some of their alloys and compounds constitute a class by themselves and are called ferromagnetic substances.
Prior to 1830, little was known of the process other than that organic compounds generally yielded tarry and solid matters, but the discoveries of Liebig and Dumas (of acetone from acetates), of Mitscherlich (of benzene from benzoates) and of Persoz (of methane from acetates and lime) brought the operation into common laboratory practice.
Proust, on the other hand, maintained that compounds always contain definite quantities of their constituent elements, and that in cases where two or more elements unite to form more than one compound, the proportions in which they are present vary per sallum, not gradually.
Pyrrol is readily converted into pyridine derivatives by acting with bromoform, chloroform, or methylene iodide on its potassium salt, t3-brom-and O-chlorpyridine being obtained with the first two compounds, and pyridine itself with the last.
Recent researches have shown that the law originally proposed by Kopp - " That the specific volume of a liquid compound (molecular volume) at its boiling-point is equal to the sum of the specific volumes of its constituents (atomic volumes), and that every element has a definite atomic value in its compounds " - is by no means exact, for isomers have different specific volumes, and the volume for an increment of CH 2 in different homologous series is by no means constant; for example, the difference among the esters of the fatty acids is about 57, whereas for the aliphatic aldehydes it is 49.
Reference should be made to the separate articles on the different elements and the more important compounds for their preparation, properties and uses.
Regnault confirmed Neumann's observations, and showed that the molecular heat depended on the number of atoms present, equiatomic compounds having the same molecular heat.
Regnault executed a careful redetermination of the specific heats of all the elements obtainable, and of many compounds - solids, liquids and gases.
Rejecting the old notion that plants derive their nourishment from humus, he taught that they get carbon and nitrogen from the carbon dioxide and ammonia present in the atmosphere, these compounds being returned by them to the atmosphere by the processes of putrefaction and fermentation - which latter he regarded as essentially chemical in nature - while their potash, soda, lime, sulphur, phosphorus, &c., come from the soil.
Resin soaps are compounds of soda or potash with the complex acids (chiefly abietic) of which coniferous resins consist.
Restricting ourselves to compounds resulting from the fusion of benzene rings, we have first to consider naphthalene, C10H8, which consists of two benzene rings having a pair of carbon atoms in common.
Rose also carried out experiments on the decomposition of cryolite, and expressed an opinion that it was the best of all compounds for reduction; but, finding the yield of metal to be low, receiving a report of the difficulties experienced in mining the ore, and fearing to cripple his new industry by basing it upon the employment of a mineral of such uncertain supply, Deville decided to keep to his chlorides.
Rotating zinc cathodes were used, with scrapers to prevent the accumulation of a layer of insoluble magnesium compounds, which would otherwise increase the electrical resistance beyond reasonable limits.
Several different products may be obtained by the reduction of the aromatic nitro compounds, the substances formed in any particular case depending on the conditions of experiment.
Should it be thought that the traces of the more valuable sorts of plant food (such as compounds of nitrogen, phosphates, and potash salts) existing in ordinary brook or river water can never bring an appreciable amount of manurial matter to the soil, or exert an appreciable effect upon the vegetation, yet the quantity of water used during the season must be taken into account.
Similar systems of symbols, but elaborated to include compounds, appear in Greek MSS.
Similarly a CH group may be replaced by a nitrogen atom with the production of compounds of similar stability; thus benzene gives pyridine, naphthalene gives quinoline and isoquinoline; anthracene gives acridine and a and 3 anthrapyridines.
Similarly he represented the reactions investigated by Liebig and Wehler on benzoyl compounds as double decompositions.
Similarly, by taking the difference of the molecular heats of compounds differing by one constituent, the molecular (or atomic) heat of this constituent is directly obtained.
Similarly, pentane, C 5 H 12, and hexane, C6H14, may exist in three and five theoretically isomeric forms respectively; confirmation of this theory is supplied by the fact that all these compounds have been obtained, but no more.
Since all soluble lead compounds are strong cumulative poisons, danger is involved in using lead cisterns or pipes in the distribution of pure waters.
Since heats of formation afford such convenient data for calculation on the above method, they have been ascertained for as many compounds as possible.
Since these compounds are essential to plant life, it becomes necessary to replace the amount abstracted from the soil, and hence a demand for nitrogenous manures was created.
Solutions were not distinguished from definite chemical compounds till John Dalton discovered the laws of definite and multiple proportions, but many earlier observations on the solubility of solids in water and the density of the resulting solutions had been made.
Some algae, however, seem to flourish better in the presence of organic compounds.
Some of these insoluble compounds can be detected by their colour and particular reactions.
South, east and west of the city are the gold mines, indicated by tall chimneys, battery houses and the compounds of the labourers.
Specific Heat and Composition.-The nature and experimental determination of specific heats are discussed in the article Calorimetry; here will be discussed the relations existing between the heat capacities of elements and compounds.
Starting with the three isomeric compounds, he found that one gave two tribrombenzenes, another gave three, while the third gave only one.
Strong oxidation breaks the benzene complex into such compounds, as carbon dioxide, oxalic acid, formic acid, &c.; such decompositions are of little interest.
Such a series of typical compounds are the benzene dicarboxylic acids (phthalic acids), C 6 H 4 (000H) 2.
Such are the compounds SbNa 3, BiNa 3, PbNa2, SnNa 4.
Such isomerism, named stereoisomerism (q.v.),hasbeen assiduously developed during recentyears; it prevails among many different classes of organic compounds and many examples have been found in inorganic chemistry.
Such spectra seem to be characteristic of complex molecular structure, as they appear when compounds are raised to incandescence without decomposition, or when we examine the absorption spectra of vapours such as iodine and bromine and other cases where we know that the molecule consists of more than one atom.
Sulphur analogues of these oxygen compounds are known.
Sulphur, phosphorus, carbon compounds, and the alkali metals react violently with the gas, taking fire with explosive decomposition.
Systems which are generally unsaturated compounds, often of considerable stability, and behave as nuclei; these compounds constitute a well-individualized class exhibiting closer affinities to benzenoid substances than to the open-chain series.
Technically he was not a chemist; he did not concern himself either with the composition of his compounds or with an explanation of what occurred in their making.
Technology compounds over time.
That he found out some new compounds is certain; but not one great and marked discovery can be ascribed to him.
That this particular feature belongs to carbon compounds is due to a property of carbon which characterizes the whole of organic chemistry, i.e.
The 2.3 derivatives are somewhat unstable compounds, since on heating they readily give up two hydrogen atoms. Tetrahydropyrazines of the 1.2.
The acid finds considerable use in organic chemistry, being employed to discriminate between the different types of alcohols and of amines, and also in the production of diazo, azo and diazo-amino compounds.
The action of these acids on many metals was also studied; Glauber obtained zinc, stannic, arsenious and cuprous chlorides by dissolving the metals in hydrochloric acid, compounds hitherto obtained by heating the metals with corrosive sublimate, and consequently supposed to contain mercury.
The affixes -ous and sub- refer to the compounds containing more of the positive element, -ic and per- to those containing less.
The analysis of organic compounds is also noticed.
The astringent principle is a peculiar kind of tannic acid, called by chemists quercitannic, which, yielding more stable compounds with gelatine than other forms, gives oak bark its high value to the tanner.
The atomic weight of silicon has been determined usually by analysis of the halide compounds or by conversion of the halides into silica.
The azo compounds are intensely coloured, but are not capable of being used as dyestuffs unless they contain salt-forming, acid or basic groups.
The azo-group is particularly active, both the aliphatic and aromatic compounds being coloured.
The beginning of the 19th century witnessed the discovery of certain powerful methods for the analysis of compounds and the isolation of elements.
The beginning of the i 9th century was attended by far-reaching discoveries in the nature of the composition of compounds.
The bodies SbNa 3, BiNa3, SnNa 4, compounds of iron and molybdenum and many other substances, have also been isolated in this way.
The brilliant researches of Frankland on the organo-metallic compounds, and his consequent doctrine of saturation capacity or valency of elements and radicals, relieved Kolbe's views of all obscurity.
The carbon compounds of the latter are of no direct nutritive value to the succeeding crop, but the decaying vegetable tissues very greatly assist in retaining moisture in light sandy soils, and in clay soils also have a beneficial effect in rendering them more open and allowing of better drainage of superfluous water and good circulation of fresh air within them.
The carbonate, being insoluble in strong alcohol (and many other liquid organic compounds), is much used for dehydration of the corresponding aqueous preparations.
The carboxyl group constitutes another convenient startingpoint for the orientation of many types of organic compounds.
The chief importance of nitrogenous compounds depends upon their assimilation by living plants, which, in their development, absorb these compounds from the soil, wherein they are formed mainly by the action of nitrifying bacteria.
The chlorine reacts with the caustic soda, forming sodium hypochlorite, and this in turn, with an excess of chlorine and at higher temperatures, becomes for the most part converted into chlorate, whilst any simultaneous electrolysis of a hydroxide or water and a chloride (so that hydroxyl and chlorine are simultaneously liberated at the anode) also produces oxygen-chlorine compounds direct.
The compounds containing this radical are treated under other headings; the hydride is better known as ethane, the alcohol, C 2 H 5 OH, is the ordinary alcohol of commerce, and the oxide (C 2 H 5) 2 O is ordinary ether.
The compounds formed in the first case, which may be either definite chemical compounds or solid solutions, are discussed under Alloys; in this place only combinations with non-metals are discussed, it being premised that the free metal takes part in the reaction.
The compounds in general, especially those originally made for Chinese labourers, are well built, comfortable, and fulfil every hygienic requirement.
The compounds of ammonia thus formed from the complex substances by many varied kinds of micro-organisms are ultimately oxidized into nitrates.
The compounds of magnesium are not absorbed into the blood in any appreciable quantity, and therefore exert no remote actions upon other functions.
The compounds of mercury attracted considerable attention, mainly on account of their medicinal properties; mercuric oxide and corrosive sublimate were known to pseudo-Geber, and the nitrate and basic sulphate to " Basil Valentine."
The constitution of the benzene ring, the isomerism of its derivatives, and their syntheses from aliphatic or openchain compounds, are treated in the article Chemistry.
The constitution of the oxyazo compounds has attracted much attention, some chemists holding that they are true azophenols of the type R N 2 R l OH, while others look upon them as having a quinonoid structure, i.e.
The corresponding potash compounds are not manufactured in the United Kingdom, but exclusively in Germany (from potassium chloride and from the mother-liquor of the strontia process in the manufacture of beetroot sugar) and in France (from vinasse).
The diortho and dipara dinitro compounds result from the action of alcoholic potash on orthoand para-nitrobenzyl chlorides.
The doctrine of copulae was discarded, and in 1859 emphasis was given to the view that all organic compounds were derivatives of inorganic by simple substitution processes.
The electrolytic reduction of the aromatic nitro compounds gives rise to substituted hydroxylamines which are immediately transformed into aminophenols or amines.
The elements which play important parts in organic compounds are carbon, hydrogen, nitrogen, chlorine, bromine, iodine, sulphur, phosphorus and oxygen.
The female constructs on a stone a series of cells, built of cement, which she compounds of particles of earth, minute stones and her own saliva.
The first class includes those substances which require no preliminary treatment, and comprises the amides and ammonium compounds, pyridines, quinolines, alkaloids, albumens and related bodies; the second class requires preliminary treatment and comprises, with few exceptions, the nitro-, nitroso-, azo-, diazoand amidoazo-compounds, hydrazines, derivatives of nitric and nitrous acids, and probably cyanogen compounds.
The freezingpoint curve sometimes indicates the existence of chemical compounds.
The fundamental chemical classification of matter, on the other hand, recognizes two groups of substances, namely, elements, which are substances not admitting of analysis into other substances, and compounds, which do admit of analysis into simpler substances and also of synthesis from simpler substances.
The gradual accumulation of data referring to organic compounds brought in its train a revival of the discussion of atoms and molecules.
The graphical representation of the properties of alloys can be extended so as to record all the changes, thermal and chemical, which the alloy undergoes after, as well as before, solidification, including the formation and breaking up of solid solutions and compounds.
The great number and striking character of the compounds of this group of metals have formed the subject of many investigations, and already there is a most voluminous literature.
The hydrogen in the primary and secondary nitro compounds which is attached to the same carbon atom as the nitro group is readily replaced by bromine in alkaline solution.
The introduction of hydroxyl groups into the benzene nucleus gives rise to compounds generically named phenols, which, although resembling the aliphatic alcohols in their origin, differ from these substances in their increased chemical activity and acid nature.
The isolation of these compounds is a powerful argument in favour of the Hantzsch hypothesis which requires the existence of these three different types, whilst the Bamberger-Blomstrand view only accounts for the forma tion of two isomeric cyanides, namely, one of the normal diazonium type and one of the iso-diazocyanide type.
The Kassner process for the manufacture of oxygen depends upon the formation of calcium plumbate, Ca2Pb04, by heating a mixture of lime and litharge in a current of air, decomposing this substance into calcium carbonate and lead dioxide by heating in a current of carbon dioxide, and then decomposing these compounds with the evolution of carbon dioxide and oxygen by raising the temperature.
The language now consists of about 15,000 words, of which compounds of two monosyllabic words and appropriations from foreign sources form a very large part.
The limits of space prevent any systematic account of the separation of the rare metals, the alkaloids, and other classes of organic compounds, but sources where these matters may be found are given in the list of references.
The lixiviation of the blackash requires great care, as the calcium sulphide is liable to be changed into soluble calcium compounds, which immediately react with sodium carbonate and destroy a corresponding quantity of the latter, rendering the soda weaker and impure.
The molecular volume is additive in certain cases, in particular of analogous compounds of simple constitution.
The mono-nitro compounds are stable and distil without decomposition; they have a pale yellow colour and possess an agreeable odour.
The most simple case is presented by the two platinum compounds PtC12(NH3)2, the platosemidiammine chloride of Peyrone, and the platosammine chloride of Jules Reiset, the first formed according to the equation PtC1 4 K 2 + 2NH 3 = PtCl 2 (NH 3) 2 + 2KC1, the second according to Pt(NH 3) 4 C1 2 =PtC1 2 (NH 3) 2 +2NH 3, these compounds differing in solubility, the one dissolving in 33, the other in 160 parts of boiling water.
The muscle is a machine for utilizing the energy contained in its own chemical compounds.
The new form takes on the characters of that from which it arose; exhibits the same power of propagating itself by means of an offshoot; and, sooner or later, like its predecessor, ceases to live, and is resolved into more highly oxidated compounds of its elements.
The nitro compounds are colourless, somewhat pleasant smelling liquids, which distil without decomposition and possess boiling points much higher than those of the isomeric nitrous esters.
The older observers, noticing the heat effects which often accompany dissolution, regarded solutions as chemical compounds of varying composition.
The organic derivatives of silicon resemble the corresponding carbon compounds except in so far that the silicon atom is not capable of combining with itself to form a complex chain in the same manner as the carbon atom, the limit at present being a chain of three silicon atoms. Many of the earlier-known silicon alkyl compounds were isolated by Friedel and Crafts and by Ladenburg, the method adopted consisting in the interaction of the zinc alkyl compounds with silicon halides or esters of silicic acids.
The orientation of higher substitution derivatives is determined by considering the diand tri-substitution compounds into which they can be transformed.
The oxidation of benzaldehyde to benzoic acid when exposed to air is not one of ordinary oxidation, for it has been observed in the case of many compounds that during such oxidation, as much oxygen is rendered " active " as is used up by the substance undergoing oxidation; thus if benzaldehyde is left for some time in contact with air, water and indigosulphonic acid, just as much oxygen is used up in oxidizing the indigo compound as in oxidizing the aldehyde.
The oxide and carbonate of magnesium are also invaluable as antidotes, since they form insoluble compounds with oxalic acid and salts of mercury, arsenic, and copper.
The oxyazo compounds are prepared by adding a solution of a diazonium salt to a cold slightly alkaline solution of a phenol.
The oxychloride, bromides, and other compounds were subsequently discovered; here we need only notice Moissan's preparation of the trifluoride and Thorpe's discovery of the pentafluoride, a compound of especial note, for it volatilizes unchanged, giving a vapour of normal density and so demonstrating the stability of a pentavalent phosphorus compound (the pentachloride and pentabromide dissociate into a molecule of the halogen element and phosphorus trichoride).
The peroxide, Ru04, is formed when a solution of potassium ruthenate is decomposed by chlorine, or by oxidizing ruthenium compounds with potassium chlorate and hydrochloric acid, or with potassium permanganate and sulphuric acid.
The placer-miner's cradle and rocking-trough were replaced by puddling troughs stirred by a revolving comb worked by horse power; reservoirs were constructed for the scanty water-supply, bucket elevators were introduced to carry away the tailings; and the natives were confined in compounds.
The poem is evidently intended to display the writer's knowledge of obscure names and uncommon myths; it is full of unusual words of doubtful meaning gathered from the older poets, and many long-winded compounds coined by the author.
The products formed by the action of the Grignard reagent with the various types of organic compounds are usually thrown out of solution in the form of crystalline precipitates or as thick oils, and are then decomposed by ice-cold dilute sulphuric or acetic acids, the magnesium being removed as a basic halide salt.
The products of the action of nitric acid on cellulose are not nitro compounds in the sense that picric acid is, but are nitrates or nitric esters.
The purity of the carbide entirely depends on the purity of the material used in its manufacture, and before this fact had been fully grasped by manufacturers, and only the purest material obtainable employed, it contained notable quantities of compounds which during its decomposition by water yielded a somewhat high pro portion of impurities in the acetylene generated from it.
The purity of the compounds thus obtained is checked by spectroscopic observations.
The putrefaction of the latter sets free sulphuretted hydrogen, which then acts on the iron compounds, precipitating ferrous sulphide.
The quinonoid structure of many coloured compounds has been proved experimentally, as, for example, by Hewitt for the benzene-azo-phenols, and Hantzsch for triaminotriphenyl methane and acridine derivatives; but, at the same time, many substances cannot be so explained.
The same author wrote the articles on the manufacture of sodium and potassium compounds and on chlorine in Thorpe's Dictionary of Applied Chemistry (3 vols., 1890-1893).
The same difference attends the introduction of the methyl group into many classes of compounds, for example, the paraffins, olefines, acetylenes, aromatic hydrocarbons, alcohols, aldehydes, ketones and esters, while a slightly lower value (157.1) is found in the case of the halogen compounds, nitriles, amines, acids, ethers, sulphides and nitro compounds.
The scientific study of salts dates from this period, especial interest being taken in those compounds which possessed a medicinal or technical value.
The second prediction is the possibility of metamerism, and the number of metamers, in a given case among compounds, which are realizable.
The simplest aliphatic compounds, such as diazo-methane, diazoethane, and azo-formic acid, are yellow; the diamide of the latter acid is orange-red.
The stronger argument against the ethylenoid linkages demanded by Kekule's formula is provided by the remarkable stability towards oxidizing and reducing agents which characterizes all benzenoid compounds.
The substances which we at present term anhydrous acids (acid oxides) only become, for the most part, capable of forming salts with metallic oxides after the addition of water, or they are compounds which decompose these oxides at somewhat high temperatures."
The sulphur compounds of copper are, however, the most valuable from the economic point of view.
The sulphur was by these converted partly into gaseous sulphuretted hydrogen, partly into soluble polysulphides, thiosulphates and other soluble compounds, and in all shapes caused a nuisance which became more and more intolerable as the number and size of alkali works increased.
The term "alloy" does not necessarily imply obedience to the laws of definite and multiple proportion or even uniformity throughout the material; but some alloys are homogeneous and some are chemical compounds.
The term allotropy has also been applied to inorganic compounds, identical in composition, but assuming different crystallographic forms. Mercuric oxide, sulphide and iodide; arsenic trioxide; titanium dioxide and silicon dioxide may be cited as examples.
The tetroxide, 0s04, is formed when osmium compounds are heated in air, or with aqua regia, or fused with caustic alkali and nitre.
The three primary members are furfurane, thiophene and pyrrol, each of which contains four methine or CH groups, and an oxygen, sulphur and imido (NH) member respectively; a series of compounds containing selenium is also known.
Their interior is divided into a series of compounds, each entered through a flat-roofed audience chamber.
Their waters are saturated with saline compounds, which in some cases have considerable commercial value.
Theoretical speculations were revived by Lavoisier, who, having explained the nature of combustion and determined methods for analysing compounds, concluded that vegetable substances ordinarily contained carbon, hydrogen and oxygen, while animal substances generally contained, in addition to these elements, nitrogen, and sometimes phosphorus and sulphur.
There also exists an extensive class of compounds termed the " heterocyclic series " - these compounds are derived from ring systems containing atoms other than carbon; this class is more generally allied to the aromatic series than to the aliphatic.
There are also reasons for including such compounds as muscarine, choline, neurine and betaine in this group.
These alkyl substitution products are important, for they lead to the synthesis of many organic compounds, on account of the fact that they can be hydrolysed in two different ways, barium hydroxide or dilute sodium hydroxide solution giving the socalled ketone hydrolysis, whilst concentrated sodium hydroxide gives the acid hydrolysis.
These are colourless crystalline compounds, which are most readily prepared by passing ammonia gas into an ethereal solution of the aldehyde.
These compounds also afford examples of the fact that, generally speaking, those compounds are most readily formed, and are most stable, in the formation of which the most heat is developed.
These compounds are both decomposed by water, the former giving dichloraceto-trichlorcrotonic acid (4), which on boiling with water gives dichlormethylvinyl-a-diketone (5).
These compounds are got into solution either as chlorides or sulphates, and from either of these salts the metal can be readily obtained.
These compounds are insoluble in ether, are non-inflammable and exceedingly reactive.
These compounds closely resemble the trichloride in their methods of preparation and their properties, forming oxyhaloids with water, and double compounds with ammonia, &c.
These compounds differ in their behaviour to heat.
These compounds generally behave as ketones; but at the same time they may act as alcohols, i.e.
These compounds may be considered as 5-triazolones, a series of isomeric 3-triazolones resulting from the condensation of phenylsemicarbazide with aromatic aldehydes in the presence of an oxidant.
These compounds may be regarded as oxides in just the same way as the alcohols are regarded as hydroxides.
These compounds retain their aliphatic nature, and are best classified with open-chain compounds, into which, in general, they are readily converted.
These form the principal natural sources of sodium compounds - the chloride as rock salt and in sea-water being of, such predominating importance as quite to outweigh all the others.
These four elements show a great resemblance to one another in their general chemical behaviour, and in that of their compounds, whilst their physical properties show a gradual transition.
These last two compounds are termed unsaturated, whereas ethane is saturated.
These relations have been more thoroughly tested in the case of organic compounds, and the results obtained agree in some measure with the deductions from molecular volumes.
These salts are like those of tin; and the resemblance to this metal is clearly enhanced by the study of the alkyl compounds.
These stars are also believed to have a comparatively low surface temperature, and the bands are attributed to the presence of compounds of carbon.
These sulphides are much less hygroscopic than the corresponding caesium compounds.
These uniform solid solutions must not be mistaken for chemical compounds; they can, within limits, vary in composition like an ordinary liquid solution.
These values hold fairly well when compared with the experimental values determined from other compounds, and also with the molecular volumes of the elements themselves.
They are compounds which greatly resemble the mixed ethers of the aliphatic series.
They are crystalline, hygroscopic compounds and are employed for the manufacture of the naphthols.
They are feeble basic compounds which distil unchanged.
They are readily converted into the isomeric aminoazo compounds, either by standing in alcoholic solution, or by warming with a mixture of the parent base and its hydrochloride;.
They are unstable compounds which readily split into the red salt and the free acid on standing.
They behave as unsaturated compounds, combining with oxygen to form peroxides and with the halogens to form triarylmethane halides.
They discriminate between the red or erythro-salts, which are well crystallized, very explosive and unstable compounds, and which regenerate the colourless nitrolic acid on the addition of dilute mineral acids, and the leuco-salts, which are colourless salts obtained by warming the erythro-salts or by exposing them to direct sunlight.
They form characteristic compounds with mercuric and auric chlorides.
They may also be obtained by the oxidation of azo compounds.
They may be prepared by the reduction of nitro compounds in alkaline solution (using zinc dust and alkali, or a solution of an alkaline stannite as a reducing agent); by oxidation of hydrazo compounds; or by the coupling of a diazotized amine and any compound of a phenolic or aminic type, provided that there is a free para position in the amine or phenol.
This and other facts connected with the stability of benzenoid compounds are clearly shown when we consider mixed aliphatic-aromatic hydrocarbons, i.e.
This and other reasons led to his rejection of the dualistic hypothesis and the adoption, on the ground of probability, and much more from convenience, of the tenet that " acids are particular compounds of hydrogen, in which the latter can be replaced by metals "; while, on the constitution of salts, he held that " neutral salts are those compounds of the same class in which the hydrogen is replaced by its equivalent in metal.
This compound condenses in alkaline solution with compounds containing the grouping - CH 2 - CO - to form quinoline or its derivatives; thus, with acetaldehyde it forms quinoline, and with acetone, a-methyl quinoline.
This conception has rendered possible a clear idea of the linking or internal structure of the molecule, for example, in the most simple case, methane, CH 4, is expressed by H H-C-H H It is by this conception that possible and impossible compounds are at once fixed.
This conception led Kekule to his "closed-chain" or "ring" theory of the constitution of benzene which has been called the "most brilliant piece of prediction to be found in the whole range of organic chemistry," and this in turn led in particular to the elucidation of the constitution of the "aromatic compounds," and in general to new methods of chemical synthesis and decomposition, and to a deeper insight into the composition of numberless organic bodies and their mutual relations.
This connexion of isomerism with resistant linking, and of this with high valency, explains, in considerable measure, why inorganic compounds afforded, as a rule, no phenomena of this kind until the systematic investigation of metallic compounds by Werner brought to light many instances of isomerism in inorganic compounds.
This fact explains the so-called "catalytic" action of acids and bases in decomposing such compounds as the esters.
This generalization was of great value inasmuch as it permitted the deduction of the atomic weight of a non-gasifiable element from a study of the densities of its gasifiable compounds.
This list is not exhaustive; other products are given in Gustav Mann, Chemistry of the Proteids (1906), to which reference should be made for a complete account of this class of compounds.
This material must be picked out, as such underburnt stuff contains free lime or unsaturated lime compounds.
This property is the liberation of some of the energy contained in the chemical compounds of the cells in such a way as to give mechanical work.
This section includes a brief history of the subject, and proceeds to treat of the principles underlying the structure and interrelations of organic compounds.
This theory brought together, as it were, the most varied compounds, and stimulated inquiry into many fields.
Thomsen deduces the actual values of X, Y, Z to be 14.71, 13.27 and zero; the last value he considers to be in agreement with the labile equilibrium of acetylenic compounds.
Those not containing a nitro group may be prepared by the oxidation of the corresponding mixed hydrazo compounds with mercuric oxide.
Three such compounds are possible according to the number of valencies acting directly between the carbon atoms. Thus, if they are connected by one valency, and the remaining valencies saturated by hydrogen, we obtain the compound H 3 C CH 3, ethane.
Thus in interpreting complicated freezing point curves, we must look for chemical compounds where the curve shows a maximum, and for a eutectic or cryohydrate where two curves meet at a minimum point.
Tin compounds when heated on charcoal with sodium carbonate or potassium cyanide in the reducing blowpipe flame yield the metal and a scanty ring of white Sn02.
To him is also due a rigorous examination of the nature of elements and compounds; he held the same views that were laid down by Boyle, and with the same prophetic foresight predicted that some of the elements which he himself accepted might be eventually found to be compounds.
Triphenylmethyl also combines with ethers and esters, but the compounds so formed are unsaturated.
Unsaturated aldehydes are also known, corresponding to the olefine alcohols; they show the characteristic properties of the saturated aldehydes and can form additive compounds in virtue of their unsaturated nature.
Until recently the vast subject of inter-metallic compounds has been an unopened book to chemists.
Various compounds of the alkali metals with bismuth, antimony, tin and lead have been prepared in a pure state.
Various compounds of the word are used, e.g.
Villiger (Be y ., 1901, 34, pp. 2679, 3612) showed that many organic compounds (ethers, alcohols, aldehydes, ketones, &c.) behave towards acids, particularly the more complex acids, very much like bases and yield crystallized salts in which quadrivalent oxygen must be assumed as the basic element.
We are now ready to study a case where several compounds are formed between the two components.
We can sometimes obtain definite compounds in a pure state by the action of appropriate solvents which dissolve the rest of the alloy and do not attack the crystals of the compound.
We do not yet know whether such absolute blending is possible or not, or whether all apparent blending is only a more or less minutely subdivided " mosaic " of non-combinable characters of the parents, in fact whether the combinations due to heredity in reproduction are ever analogous to chemical compounds or are always comparable to particulate mixtures.
We have here a comparatively simple case, as the metals do not form compounds.
We may also notice that thio-ethers combine with alkyl iodides to form sulphide or sulphonium compounds, R3; SI.
We may, in fact, consider that the descriptive study of the various halogen compounds dates from about this time.
We now proceed to discuss molecular heats of compounds, that is, the product of the molecular weight into the specific heat.
We now proceed to discuss the types of aliphatic compounds; then, the characteristic groupings having been established, an epitome of their derivatives will be given.
Whatever were the means employed to rid air of accompanying oxygen, a uniform value of the density was arrived at, and this value was z% greater than that appertaining to nitrogen extracted from compounds such as nitrous oxide, ammonia and ammonium nitrite.
When acetylene was first introduced on a commercial scale grave fears were entertained as to its safety, it being represented that it had the power of combining with certain metals, more especially copper and silver, to form acetylides of a highly explosive character, and that even with coal gas, which contains less than i %, such copper compounds had been known to be formed in cases where the gas-distributing mains were composed of copper, and that accidents had happened from this cause.
When magnesium is heated in fluorine or chlorine or in the vapour of bromine or iodine there is a violent reaction, and the corresponding halide compounds are formed.
When reduced (in acid solution) they yield amines; distillation with reduced iron gives azo compounds, and warming with ammonium sulphide gives hydrazo compounds.
When the two components form chemical compounds with each other, the phenomena of mutual solubility become more complex.
When Wohler, in 1825, analysed his cyanic acid, and Liebig his quite different fulminic acid in 1824, the composition of both compounds proved to be absolutely the same, containing each in round numbers 28% of carbon, 33% of nitrogen, 37% of oxygen and 2% of hydrogen.
Whereas carbon renders isomerism possible in organic compounds, cobalt and platinum are the determining elements in inorganic chemistry, the phenomena being exhibited especially by complex ammoniacal derivatives.
While successfully investigating the solid elements and their compounds gravimetrically, Berzelius was guilty of several inconsistencies in his views on gases.
While the discovery of bromine and the preparation of many of its compounds was his most conspicuous piece of work, Balard was an industrious chemist on both the pure and applied sides.
Williamson showed how alcohol and ether were to be regarded as derived from water by substituting one or both hydrogen atoms by the ethyl group; he derived acids and the acid anhydrides from the same type; and from a comparison of many inorganic and the simple organic compounds he concluded that this notion of a " water-type " clarified, in no small measure, the conception of the structure of compounds.
With iodine compounds, iodic acid is likely to be formed, and hence the solution must be reduced with sulphurous acid before precipitation with silver nitrate.
With reference to their chemical physiology, the gelatinization of the cell-wall, which is so marked a feature, is doubtless attributable to the occurrence along with cellulose of pectic compounds.
With substances prone to discolorization, as, for example, certain amino compounds, the operation may be conducted in an atmosphere of carbon dioxide, or the water may be saturated with sulphuretted hydrogen.
With the Grignard reagent, they form addition compounds which on the addition of water yield tertiary alcohols, except in the case of ethyl formate, where a secondary alcohol is obtained.
Zincke; and his researches have led to the discovery of many chlorinated oxidation products which admit of decomposition into cyclic compounds containing fewer carbon atoms than characterize the benzene ring, and in turn yielding openchain or aliphatic compounds.