92 
Dr. Thomson on Oxalic Acid. 
Grains. 
1. Azotic gas 35 cubic inches equivalent to 10.62 
2. Nitrous gas 32 cubic inches equivalent to 10.85 
Now, as nitric acid contains no carbon, it is obvious that the 
oxalic acid formed, and the carbonic acid evolved, must con- 
tain the whole carbon contained in 100 grains of sugar. 
Grains. 
45 grains of oxalic acid contain of carbon 14.40 
46.5 grains of carbonic acid contain of ditto 13.02 
Total 27.42 
therefore 100 grains of sugar contain 27-j grains of carbon. 
The azotic gas and nitrous gas must have been originally 
in the state of nitric acid, and must have given out oxygen 
when they were evolved. But nitric acid is composed of 
Oxygen. 
Azote - - 10.62 + 2 5 
Nitrous gas 10.85 + 45 
Therefore they must have parted with 29.5 grains of oxy- 
gen. We are at liberty to suppose that the whole of this 
oxygen went to the formation of carbonic acid. Now, 46.5 
grains of carbonic acid are composed of 
Grains. 
Oxygen - 38.5 
Carbon - - 13.0 
46.5 
From this it appears, that in the carbonic acid there were 
4 grains of oxygen more than was furnished by the nitric 
acid. • I confess I am disposed to ascribe this surplus to errors 
