The Effect on Wool of Boiling in Aqueous Solutions IIndashSolutions of Ammonium Salts with and without Ammonia

The pH values at 100d̀c. obtained by extrapolation from measurements on dilute aqueous solutions of ammonium sulphate, acetate, (diammònium) phosphate, chromate, and chloride at temperatures ranging from 18d̀c. to 80d̀c. agree approximately with the pH values at 100d̀c. calculated from the published dissociation constants of the acids, ammonium hydroxide, and water. It follows that pH measurements on The solutions at room temperatures cannot, without other data, be relied upon to indicate their pH values at 100d̀c. Ammonium salt solutions containing added ammonia can have pH values ca. 2 units lower at 100d̀c. than at 18d̀c. Ammonium sulphatendashammonia solutions of alkaline pH values8 when measured at 18d̀c. have acid pH values < 6 at 100d̀c. without loss of ammonia. Metachrome mordant solutions with room‐temperature pH values ca. 6.7–8.7 are at 100d̀c. buffered at ca. pH 6.7. Wool yarn, boiled for 3 hr. in the ammonium salt and ammonia solutions (excluding chromate and chloride) at controlled pH values and at concentrations simulating commercial dyeing, gives degrees of modification, as measured by wet breaking load and content of disulphide sulphur, in fair agreement with the salt contents of the solutions and the pH values at 100d̀c. but not with the pH values at room temperature.