482 Dr. Ure on the ultimate analysis , &c. 
13.125 grains of crystallized ferroprussiate of potash afford 
12.33 grains of nitre, which contain 5.8 of potash.* By heating 
nitric acid in excess on 21 grains of ferroprussiate of lead, I 
obtained 2.625 grains of peroxide of iron, equivalent to 1.8375 
of the metal. Hence I infer, that the iron in the ferroprussiate 
of lead is in the metallic state ; for the joint weights of the 
carbon and azote contained in 7 grains of the dry acid is 
5.0477; and the difference, 1.9523, approaches too closely 
to the above quantity, 1.8375, for us to suppose the metal to 
be in the state of protoxide. In fact, 2.625 parts of peroxide 
x 0.9 = 2.3625 of protoxide, is a quantity much beyond what 
experiment shows to be present. 
* By careful desiccation, 1.69 grains of water, may be separated from 13.125 
grains of the salt. 
