Brown — Work on the Interaction of Hydrochloric Acid. 47 



ides than in their absence, the readings of the present paper 

 are considerably greater than corresponding readings in the 

 previous paper. These differences can be explained on the 

 evident supposition that the oxidation of the oxalic acid by the 

 chlorine was more extensive in the experiments recorded in 

 this paper than in those of Table I of the previous paper, for 

 these differences disappear when the chlorine is removed from 

 the sphere of action, the differences between the readings of 

 Tables II and III of the previous paper on the one hand and 

 those of Table II of the present paper on the other being 

 small and in all probability clue to differences in the strength 

 of the permanganate solution used. The experiments of this 

 paper were made with as little shaking as possible to avoid ex- 

 pulsion of chlorine mechanically, and allow the chlorine to 

 exert its maximum oxidizing effect on the oxalic acid during 

 the time of the titration. These variations show still more 

 conclusively the non-concordance likely in Wagner's process, 

 and the dependence of results on the oxidizing action of the 

 chlorine. 



The conclusion must be drawn, then, that Wagner's results 

 with each of the salts which he regards as catalyzers are in all 

 cases largely dependent on the oxidizing action of the chlorine 

 held in solution. With ferric chloride, cadmium chloride, and 

 chlor-auric acid, the assumed catalytic effect of chlor-metal 

 acids formed by the union of the metallic chlorides with hydro- 

 chloric acid, which are more easily oxidized by potassium per- 

 manganate than is hydrochloric acid, is unsubstantiated. With 

 these three compounds the apparent catalytic effect is due 

 entirely to the chlorine retained in solution. With chromic 

 chloride and chlor-platinic acid the observed differences are 

 due partly to the chlorine retained in solution but partly also 

 to the total reduction of the residual oxides of manganese. 

 With platinic chloride the action is apparently catalytic, this 

 compound exerting a reducing action on the higher oxides of 

 manganese formed in the presence of the other compounds. 

 With chromic chloride the action is not catalytic, the assumed 

 catalyzer being oxidized to chromate, thus losing its identity, 

 as is not the case with a true catalyzer. 



Another series of experiments was made to ascertain whether 

 any difference in the amount of higher oxides of manganese 

 formed in the presence of ferric chloride, cadmium chloride, 

 or chlor-auric acid, or in the amount of chromate formed in the 

 presence of chromic chloride, is caused by the removal of 

 chlorine in the experiments of Table II. Experiments were 

 made as were those of Table I, the digestion being continued 

 one hour without the removal of chlorine, and the chlorine 

 then removed by blowing a current of air through the solution 

 for one-half hour. Oxalic acid was then added and perman- 



