AT THE MOMENT OF CHEMICAL CHANGE. 
781 
result. But as the conclusions which they indicated were afterwards brought out 
and confirmed by experiments not open to these objections, it would be superfluous 
to give in their case also the numerical details of the determinations. As however 
they threw much light on the general nature of the inquiry, I cannot omit some ac- 
count of them. 
In the Tables which follow, I have arranged the chief results of these experiments. 
The column A. contains the amount of oxygen =-a in 100 parts of the peroxide of 
barium employed, as given by the determination with bichromate of potash. The 
column B. contains the relative loss of oxygen from the metallic oxide ; the loss, 
that is, calculated on 100 parts of the peroxide of barium. This loss ='vj/. The 
column C. contains the ratio of the quantity of oxygen in the peroxide of barium to 
the loss from the metallic oxide ; the ratio, that is, of a: and the calculated value 
of \p. In the column D. I have given the approximate ratio of the oxygen in the 
amount of peroxide of barium taken, to that in the oxide of silver or peroxide of lead 
taken in each experiment. The first Table contains the experiments made at 100° C. 
The first six experiments were made with oxide of silver, the rest with peroxide of 
lead. In the case of the peroxide of lead, the amount of oxygen lost by the peroxide 
was determined by extracting the residue after the experiment with very dilute nitric 
acid, which, leaving the peroxide, dissolves the oxide formed. The lead thus dissolved 
was estimated as sulphide. 
Experiments at 1 00° C. 
A. 
R. 
c. 
D. 
1. 
2. 
4-03 
1'65 
1-64 
5 
2 
1-61 
3:2 
CO 
4*18 
1- 95 
2- 08 
2 
1 
2-09 
3 : 2 
1 : 1 
5. 
6. 
5-85 
3-08 
2-99 
2 
1 
2-92 
AgO not weighed. 
CO 
4-32 
1-85 
1-71 
5 
2 
1*72 
5 : 4 
1 : 1 
9. 
10. 
6-10 
3*31 
3-37 
7 
4 
3-48 
PbOo not weighed. 
Classifying these ten experiments with reference to the ratios given in the third 
column, we find that they may be arranged thus : — 
5 : 2, four experiments. 
4 ; 2, four experiments. 
3^ : 2, two experiments. 
In the next Table the experiments were made below 100°; where the temperature 
is not given they were at the temperature of the air. The two last experiments were 
made with the peroxide of lead, the rest with the oxide of silver. 
