At the end of the experiment, all the gases which remained in A and B were driven over into C by lowering the reservoir M and opening the pinch-cock at D. When this was accomplished the stop-cock of C was closed and the gases brought under atmospheric pressure by bringing the mercury in C and M to the same level.
It will be seen that in this gas volume was included the air which A and B contained at the beginning of the experiment.
The oxygen evolved from the contents of the flask was determined thus: After reading off the total volume of air and oxygen and reducing to normal conditions, the total volume of oxygen was obtained by absorption with phosphorus or pyrogallol, and from the residual nitrogen could be calculated from the volume of air to be deducted the total volume of gases. The remainder is the volume of oxygen sought.”
Action of manganese dioxide
on potassium permanganate
in acid solution.
Three sets of apparatus like the one described were used.
The flask of apparatus No. I contained manganese dioxide and dilute nitric acid.
The flask of apparatus No. II contained potassium permanganate and dilute nitric acid.
The flask of apparatus No. III contained potassium permanganate and dilute nitric acid and manganese dioxide.
The manganese dioxide used in these experiments was precipitated from a solution of potassium permanganate by a dilute solution of manganous sulfate in the manner described on [page 34] and then washed and dried at 100°C.