Vortmann (Ber., 1890, 23, p. 2 753) dissolve phenol in caustic alkali, make the solution up to known volume, take an aliquot part, warm it to 60° C., and add decinormal iodine solution until the liquid is of a deep yellow colour.
The mixture is then cooled, acidified by means of sulphuric acid, and titrated with decinormal sodium thiosulphate solution.
By taking ivth or 10th of these quantities, decinormal or centinormal solutions are obtained.
The equivalent quantities), and similarly for decinormal and centinormal solutions.
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.
It is one of the "strong" acids, being ionized to the extent of about 91.4% in decinormal solution.
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.