LIX.—The affinity constants of bases as determined by the aid of methyl-orange
Journal of the Chemical Society Transactions
DURING the past thirty years, various methods have been adopted for the purpose of assigning definite values for the affinity constants of nitrogenous bases. Such methods have consisted in determining (i) the heats of neutralisation with hydrochloric acid (Berthelot, Tbomsen, Luginin, and others), (ii) the electric conductivity factors of the hydrochlorides with or without excess of either acid or base* (Walker, Bredig, Winkelblech and Lunden, and others), (iii) the catalysis of methyl acetate
... of methyl acetate by the hydrochloric acid liberated by hydrolysis (Walker and others), (iv) the inversion of sucrose similarly (Walker), (v) a coefficient of extraction method (Wood and others), (vi) a coefficient of extinction method (Lellrnann, associated with others), as also various methods of less importance and accuracy. A few words regarding such methods will suffice for the purpose of argument. As to (i), I have elsewhere pointed out the importance of correlating hydrolpis and thermoneutrality values, and of calculating out the latter in terms o€ the former by the equation proposed by * The literature of the subject has been fully collated by Lunden (Zeitsch. physikal. Chem., 1906, 54, 561 ct sep.), so it is thought necessary to give references only in special cases. * The coloration of methyl-orange by carbonic acid was first observed by Kuster (Zeitsch. anorg. Chem., 1897, 13, 136) .