The mixture is then cooled, acidified by means of sulphuric acid, and titrated with decinormal sodium thiosulphate solution.
Thus the statement that the migration constant or transport number for a decinormal solution of copper sulphate is o 632 implies that of every gramme of copper sulphate lost by a solution containing originally one-tenth of a gramme equivalent per litre when a current is passed through it between platinum electrodes, o 632 gramme is taken from the cathode vessel and o 368 gramme from the anode vessel.
To ascertain this value the volatile acids contained in 5 grammes of an oil or fat are distilled in a minutely prescribed manner, and the distilled-off acids are measured by titration with decinormal alkali.
Unfortunately, the term normal is sometimes given to solutions which are strictly decinormal; for example, iodine, sodium thiosulphate, &c. In technical analysis, where a solution is used for one process only, it may be prepared so that I cc. is equal to.