358 Dr. Prout on the ultimate composition 
it was ever entertained, and the general principle on which 
the analysis of organic products has been usually conducted, 
has been to obtain their elements in the form of binary com- 
pounds, either by destructive distillation, as was formerly 
practised ; or by combining the elements with some other 
element with which they possessed the property of forming 
definite binary compounds, from the quantity and known 
composition of which, those of the original elements might 
be readily obtained by calculation. For this latter purpose 
oxygen has been the principle usually employed, which, as is 
well known, forms water with hydrogen, and carbonic acid 
gas with carbon ; two compounds not only as well understood 
as any in chemistry, but likewise, from their physical pro- 
perties, well adapted for the purpose. When azote is involved 
other means must be adopted, which will be fully considered 
hereafter. 
The modes in which chemists have attempted to combine 
oxygen with the hydrogen and carbon of vegetable substances 
have differed very considerably. The illustrious Lavoisier 
attempted their union by burning the substance at once in 
oxygen gas, a method subsequently followed by Saussure 
and others. Afterwards the metallic oxides were employed 
for the purpose ; and Berzelius in particular informs us, that 
so early as 1807 he had tried the oxide of lead, but did not 
succeed with it.* In 1811, Gay Lussac and Thenard pub- 
lished the analysis of different organic substances made by 
means of the chlorate of potash ; and, considering the nature 
of the apparatus they employed, they obtained admirable 
approximate results.-f Berzelius, in 1814, published an 
* Annals of Philosophy, iv. 403. f Recherches Physico-chimiques, ii. 265. 
