840 
PKOFESSOE B. C. BEODIE ON THE OXIDATION AND 
The burette employed for titration with permanganate was provided with a glass 
stopcock ; it was etched and calibrated in the same manner as a tube for gas-analysis. 
The readings were made with a telescope. 
The peroxide of barium employed was prepared by precipitation, according to a method 
elsewhere described. It was free from all impurities, except a trace of carbonate. 
When a solution of peroxide of hydrogen is spoken of, it is to be understood as the 
solution of this peroxide of barium in dilute hydrochloric acid. 
The solutions of peroxide of sodium were prepared by digestion of the moist and 
freshly-precipitated hydrate of the peroxide of barium with carbonate of sodium, and 
filtration from the carbonate of barium formed, or, in some cases, by precipitation of 
the solution of peroxide of barium in hydrochloric acid by carbonate of sodium, and 
filtration. 
In the numerous experiments and calculations which have been made in the course 
of the following investigation, and of which a small part only is here recorded, I have 
been much indebted to the skill and care of my assistant, Mr. F. Schickendanz. 
1. Decomposition of a Solution of Peroxide of Hydrogen hy Permanganic Acid. 
"When a solution of permanganate of potassium is mixed with an acid solution of the 
peroxide of hydrogen, a decomposition of both substances ensues, oxygen gas is evolved, 
and a colourless solution formed containing a protosalt of manganese. 
The proportion in which the substances are decomposed in this reaction was deter- 
mined in the following manner. 
A portion of pure peroxide of barium was dissolved in very dilute hydrochloric 
acid ; a measured quantity of this solution was decomposed by hydilodic acid, and the 
amount of iodine formed estimated with sulphurous acid, according to the method of 
BujfSEX. 
A measured amount of the solution of permanganate of potassium was decomposed 
by hydriodic acid, and the iodine formed estimated by the same method. 
A measured amount of the solution of peroxide of hydrogen was decomposed by the 
solution of permanganate, which was added from the burette until the solution was 
faintly coloured. 
Now, if s be the parts of the standard iodine solution required for the decomposition 
of 1 cub. centim. of the solution of peroxide of hydrogen, and if be the parts of the 
iodine solution required for the decomposition of I cub. centim. of the solution of per- 
manganate of potassium, where s and Sj are determined according to the usual formula 
nt—t^ 
S— , 
p 
and if m be the parts of the solution of peroxide of hydrogen decomposed by the per- 
manganic acid, and m^ be the parts of the solution of permanganate required to effect 
their decomposition, and if be the ratio of the amount of oxygen evolved from the per- 
