ULTIMATE ANALYSIS OF ORGANIC MATTER. 291 



proximate principles of the vegetable kingdom in general it 

 is absent. Whence it is common to say that animal matter 

 differs from vegetable matter in this respect, that animal matter 

 consists of oxygen, hydrogen, carbon, and nitrogen ; whereas 

 vegetable matter is made up of oxygen, hydrogen, and carbon. 

 It is, in short, true that an immense proportion of the substance 

 of the vegetable kingdom cannot supply effective nourishment 

 to the higher animals ; yet that apparently non-esculent sub- 

 stance yields food to such lower animals as are provided with 

 organs fit to separate the nutritive from the non- nutritive 

 matter. 



The ultimate analysis of organic matter, both qualitative or 

 that which determines the kinds of elements, and quantitative 

 or that which settles the proportion of each element present, has 

 now been carried to great exactness ; but it would be foreign 

 to our present purpose to explain the methods resorted to for 

 this end. A few words respecting the older or first methods 

 will afford an easier explanation of the kind of operation 

 required to accomplish such an analysis. 



It was at an early period observed that vegetable matter, 

 when subjected to a destructive heat while the atmospheric air 

 was excluded, gave off much carbonic acid gas and watery 

 vapour, along with carbonic oxide, carburetted hydrogen, acetic 

 acid, and empyreumatic oil ; while the ashes contained princi- 

 pally carbonate of potassa that is to say, the vegetable body 

 was reduced to ashes consisting of carbon and carbonate of 

 potassa, with some less abundant saline matters, while nothing 

 was volatilised but bodies known to consist of oxygen, hydro- 

 gen, and carbon. It occurred to chemists that if a body capable 

 of affording oxygen freely were mingled with the vegetable 

 substance before the destructive heat was applied, the new sup- 

 ply of oxygen, together with that already existing in the body 

 under analysis, might be sufficient to convert the whole of its 



