Dr. Thomson on Oxalic Acid. 
de- 
ducts evolved, when that add is decomposed by heat, contain 
more than 3 atoms. Hence it is probable that sugar is a 
more compound body than oxalic acid, because nitric acid re- 
solves it into a variety of new compounds, one of which is 
oxalic acid. It may be worth while to examine the action of 
nitric acid on sugar, and the formation of oxalic acid, more 
closely than has hitherto been done, as the investigation will 
furnish some data for estimating the composition of sugar. 
Two hundred grains of pure crystallized sugar being 
treated with diluted nitric acid in the usual way, yielded 200 
cubic inches of carbonic acid, 6 4 cubic inches of nitrous gas, 
and 70 cubic inches of azotic gas. But these numbers, though 
the result of a good many experiments, are not to be con- 
sidered as very exact. The uncertainty depends upon the pro- 
perty which the solution has of producing more gas after the 
sugar is decomposed, at the expence of the oxalic acid formed. 
Now, it is difficult to stop at the precise point. 
The whole weight of oxalic acid, which can be obtained 
from 200 grains of sugar, amounts to 1 16 grains. If the ex- 
periment be properly conducted, the whole of the sugar is 
decomposed, or at least the quantity of residuary matter is 
small. 
From the preceding statement, there is reason to conclude 
that 100 grains of sugar, when decomposed by nitric acid, 
yield, 
Grains. 
1. Oxalic acid crystals 58 grains, or real acid 45 
2. Carbonic acid 100 cubic inches, equivalent to 46.5 
while these are evolved obviously by the decomposition of the 
nitric acid. 
N 2 
