180 
IOWA ACADEMY OF SCIENCES 
It is evident that the interaction of chloric acid and the small amount 
of hydrochloric acid produced in the study of the action of chloric acid 
on metals, is insignificant. On the other hand the hydrochloric acid 
produced may itself be effective in dissolving small quantities of some 
metals, such as magnesium and zinc. In the action of bromic acid on 
metals the results were quite different, as anticipated. As is well known 
hydrobromic and bromic acid readily react upon each other in the pro- 
portion of five molecules of the former to one of the latter setting all the 
bromine free. The hydrobromic acid is, therefore, removed, as formed 
with the liberation of bromine, but the bromine may itself react upon the 
remaining metal. 
The bromic acid used in the following experiments was made by 
Kahlbaum. It was as usual colored by bromine, which was aspirated 
off in a vacuum before use. It was free from sulphuric acid and its 
freedom from the acids of chlorine was tested by determining the ratio 
of silver to silver bromide, in which weighed amounts of pure silver 
were precipitated with hydrobromic acid made by reducing the bromic 
acid. Three experiments gave the following proportions: 
1. 
Ag 
AgBr : 
: 100 
174.09 
2. 
Ag 
AgBr : 
: 100 
174.01 
3. 
Ag 
AgBr : 
: 100 
174.19 
The average is 174.09 and the theory 174.08. 
The concentration of the acid was found to be 1.25 normal, and in 
most of the experiments it was used undiluted. In the experiments the 
apparatus was such as to permit the reaction of the acid and metal to 
take place in carbon dioxide, in order to avoid any oxidizing action of 
the air. The acid was placed in a glass-stoppered distilling flask whose 
side tube entered the neck of another distilling flask and its tip was 
placed just under the surface of a solution of potassium iodide. To the 
side arm of the second flask was connected a bulb column to absorb the 
last traces of bromine, in the dilute potassium iodide which it contained, 
The whole apparatus was filled with carbon dioxide, the stopper removed, 
the metal dropped in. It was placed in a dark closet and allowed to 
remain, usually several hours or till the metal was all dissolved. The 
bromine was then all aspirated over into the potassium iodide wuth a 
stream of air under about 50 mm. pressure. The free iodine was titra- 
ted with sodium thiosulphate and the corresponding bromine calculated. 
In the experiments described below the bromine is usually a little 
smaller than required by theory, on the supposition that the hydrobromic 
acid produced in the oxidation of the metal reacts with bromic acid 
thus: 5HBr -f HBrO^ = 3H-0 + 6Br. The deficiency amounts on the 
average to about 5 per cent, and maj'' be due to one of two causes or both. 
The bromine set free may act directly upon the remaining metal form- 
ing a bromide which would again react with bromic acid, or there may 
result the formation of some hypobromous acid, which would not distil 
over under the conditions. I regret that I have not been able to pursue 
the subject farther and hope to return to the studj^ in the near future. 
