of Atmospherical Air, Bc. 131 
able doubt.—But I proceed to the explanation of 
the Doctor’s experiments. 
Since the constituent principles of carbonic acid 
are demonstrated, both by analysis and synthesis, 
to be oxygen and pure charcoal, we cannot doubt, 
that the diminution of the air was occasioned by its 
oxygen combining with the carbon of the black 
bones, and forming the carbonic .acid which pre- 
cipitated the lime. These bones therefore could 
gain no weight, but would on the contrary lose 
some little: but, 12.0288 parts of carbon saturate 
56.687 parts of oxygen,* the loss of weight must 
have been trifling. This seems to have been the 
case ; for we are informed, that the bones rather 
lost something. . This experiment with calcined 
bones is, in reality, little else than a combustion of 
charcoal, the result of which is not to be sought for 
in the residuum of the bones, but in the carbonic 
acid which was produced: of which however Dr. 
Priestley takes no notice. 
The excess of azote in the residuum of the air, 
I ascribe to a “decomposition of the ammoniac con- 
tained in the bones; and this is rendered more pro- 
bable by the result of the experiments with iron and 
necdles, in which much less azotic gas remained, 
A portion of oxygen may also have combined with 
the bones. Through our ignorance of the origi- 
nal degree of purity of the air and of ‘the quantity 
* Chaptal, vol, 1, p. 220, 
