Brown — Work on the Interaction of Hydrochloric Acid. 57 



total KMn0 4 found showed a permanganate equivalent of only 

 - 81 cm3 as indicated in experiment marked *. It would appear, 

 therefore, that with cadmium chloride, and to a lesser extent 

 with chromic chloride, the permanganate is reduced without 

 leaving anything like a proportionate amount of chlorine in 

 solution at the close of the hour's digestion. This may be due to 

 reduction of the permanganate with liberation of oxygen, which 

 does not act on the hydrochloric acid to produce chlorine, or to 

 action of chlorine first liberated on the water giving oxygen. 

 By either of these actions there would be a loss of the chlorine 

 which goes to oxidize oxalic acid in Tables I to IV and to 

 liberate iodine from potassium iodide in Tables V and VI. To 

 ascertain whether this loss is occasioned by formation of 

 oxygen, the following experiment was made : To 100 cm3 of 

 normal hydrochloric acid were added 2 grams of cadmium 

 chloride, 10 om3 of water and the solution transferred to a 100 om8 

 burette, enough water added to completely fill the burette, 

 which required about 10 cm3 additional, and the burette inverted 

 in a porcelain dish tilled with water, the upper end of the 

 burette being carefully stoppered. Almost immediately gas 

 began to accumulate and continued to accumulate slowly for 

 about three hours, at the end of which the permanganate color 

 had disappeared. The amount of gas collected was too small 

 to admit either of qualitative or quantitative tests with the 

 crude apparatus here used. Additional experiments must, 

 therefore, be made to determine definitely whether oxygen is 

 evolved in this way. The evidence, however, so far as it goes, 

 consistently points to evolution of oxygen in the interaction of 

 hydrochloric acid and potassium permanganate in the presence 

 of cadmium chloride. The author intends to investigate this 

 point further, as well as the action of the other salts which 

 Wagner regards as catalyzers. Gooch and Danner* have 

 shown that oxygen is evolved from potassium permanganate 

 acidified with sulphuric acid. Some such action, it seems, 

 occurs in the experiments of this paper when permanganate 

 is acidified with hydrochloric acid in the presence of cadmium 

 chloride, part of the oxygen of the permanganate being 

 evolved directly instead of liberating chlorine from hydro- 

 chloric acid, or the chlorine first liberated acting on the water 

 to set free oxygen. 



The author is indebted to Prof. F. A. Gooch for much 

 advice and assistance in the preparation of this paper. 



* This Journal [3], vol. xliv, 301 (1892). 



