480 Dr. Ure on the ultimate analysis of 
or, of 2 atoms Carbon . . 1.5 . . 19.14 
3 Oxygen . . 3.0 40.72 
3 _ Water . . 3.375 . 40.14 
7.875 100.00 
Into the dry oxalate of lead these 3 atoms of water do not 
enter. Hence, I find the dry acid to be composed of 
Carbon 2 atoms . 1.5 . . 33.3 3 
Oxygen 3 . . 3.0 . . 66.66 
4.5 100.00 
or, of 1 atom carbonic acid + 1 atom carbonic oxide, as was 
first suggested, I believe, by Dobereiner. Crystallized 
oxalate of ammonia consists of 1 atom acid, 1 atom ammonia, 
and 2 atoms water = 8.875. By a gentle heat 1 atom of 
water may be separated ; and an oxalate of ammonia, as dry 
as is compatible with its neutrality, remains. 
I have analyzed, by the peroxide of copper, the citrate, 
tartrate, and oxalate of lead -; and on comparing the results 
thus obtained, with those derived from the analysis of the 
crystalline acids, I have come to the above determinations. 
Ferroprussic acid, the ferrocyanic acid of the French che- 
mists, has proved, hitherto, a stumbling block to me, in re- 
ducing the results of my experiments to the atomic theory. I 
have subjected it to very numerous trials in many states of 
combination, and have sought, with great pains, to accommo- 
date the results to the doctrine of prime equivalents ; but 
hitherto without success. The following facts, however, may 
perhaps be deemed of some consequence. 
In the first place, the prime equivalent of the crystallized 
ferroprussiate of potash is 13.12 5, compared to oxide of lead 
