138 REPORTS ON THE STATE OF SCIENCE.—1913. 
if due regard is had to the purity of the water, and the protection of the 
solution from contamination with reducing materials. At 25° a 0-1 per 
cent. aqueous solution of this chloroamine drops only a few per cent. in 
titre in the course of several weeks; at 60°, however, 50 per cent. has 
disappeared in 38:5 hours. The addition of small quantities of an acid 
(1-2 molecular proportions, which give a concentration of 0-0058-0:0116) 
increases the rate of change, which is, however, still very slow ; about 50 
per cent. of the chloroamine disappears in one month at 25°, but in less 
than a day at 60°. There is no great difference between different acids, 
including hydrochloric, in their effect. Careful examination of the re- 
actions, which lead to a fall in titre both in aqueous and highly dilute acids, 
discloses the fact that the principal change is a simple reduction of the 
chloroamine to anilide and hydrogen chloride; at the same time a small 
and very variable amount of chlorate appears. The production of chloro- 
anilides is quite subsidiary. The most obvious interpretation of the facts is 
that the chloroamine is hydrolysed : 
Ar.NCl.Ac+ H,O = HClO+Ar.NH. Ac 
and the hypochlorous acid then reduced. It is not so easy to see how 
the latter change is brought about. Both an aqueous solution of 
hypochlorous acid and also solutions containing a strong acid are quite 
stable. Moreover, the pure anilide does not reduce hypochlorous acid ; 
the sole interaction is the equilibrium represented above. It seems most 
probable that the reduction is effected by aniline arising from the hydrolysis 
of the anilide—a change which has been shown to occur, but slowly, under 
the circumstances. The hydrolysis of the anilide in pure water is yet 
slower than in acids, and hence the permanence of solutions of chloro- 
amine in this medium at ordinary temperatures. The development of the 
characteristic colour reactions of aniline with hypochlorous acid in the 
course of the change is in harmony with this suggestion. Further, aniline 
is particularly effective as a reducing agent for hypochlorous acid, since 
one molecular proportion reduces several of the acid. 
At higher concentrations of the acids (0-023 NV) the specific effect of 
hydrogen chloride appears ; but with the other acids the speed of hydro- 
lysis and reduction is merely increased. But even with very great excess 
of hydrogen chloride, when the disappearance of the chloroamine is rela- 
tively rapid, the hydrolysis and reduction can still be detected as a sub- 
sidiary reaction. ‘The formation of hydrogen chloride by reduction in the 
experiments with other acids is the obvious cause, as previously indicated, 
of the production of the small quantities of chloroanilide. 
Method of Experiment—Aqueous solutions of acetylchloroaminoben- 
zene containing about 1 gram per litre were used, the reactions being 
carried out at 25°and 60°. After more than 50 per cent. of the chloroamine 
has disappeared, the hydrogen chloride is estimated. The remaining 
chloroamine (and the very small amount of hypochlorous acid) is reduced 
by arsenite, and the chloridion weighed as silver chloride. In order to 
estimate any chlorate which has been formed from the hypochlorous acid 
the reduction in another portion is carried out by sulphite. The chloro- 
anilide is assumed to be given by difference, but it is quite possible that 
some chlorine disappeared in the oxidation of the aniline or in chlorinating 
free aniline. Some of the results are shown in Table IT. 
