analyzed by means of the nitric acid, were found by M. Vauquelin, to 

 contain T 6 ^ of pure silex indissoluble in that acid, and 0,393 of phos- 

 phate of lime dissolved in it. 



The excrements of a hen, fed, for ten days, on oats only, on being cal- 

 cined and analyzed by the same chemist, produced twice as much phos- 

 phate and carbonate of lime as was contained in the oats, with a small 

 deficiency in the quantity of silex, which might have been employed in 

 furnishing the excess of calcareous matter; a transmutation depending 

 on the absorption of an unknown principle, to the amount of nearly five 

 times in its own weight *. 



CX. A substance to be fit for our nourishment, should be capable of 

 decomposition and fermentation ; that is, capable of ^undergoing an in- 

 ward and spontaneous change, so that its elements and relations may be 

 altered. This spoutaneous susceptibility of decomposition, excludes from 

 the class of aliments, whatever is not organized and is not a part of a 

 living body, thus, mineral substances absolutely resist the action of our 

 organs, and are not convertible into their own substance. The common 

 principle extracted from alimentary substances, however varied they may 

 be, the aliment, as Hippocrates terms it, is most probably, a compound 

 highly subject to decomposition and fermentation ; this is likewise, the 

 opinion of all those who have endeavoured to determine its nature. Lorry 

 thinks it a mucous substance ; Cullen says it is saccharine ; Professor 

 Halle considers it as an hydro-carbonous oxyde, which differs from the 

 oxalic acid, only in containing a smaller quantity of oxygen. It is evi- 

 dent, that these three opinions are very much alike, since oxygen, car- 

 bon, and hydrogen, combined in different proportions, form the mucous 

 saccharine substances and the base of the oxalic acid. On analyzing the 

 animal substance, by means of the nitric acid, it is reduced to this last 

 base, by depriving it of a considerable quantity of azote which constitutes 

 its most remarkable character. 



But whence comes this enormous quantity of azotef ? How happens it, 

 that the flesh of a man living exclusively on vegetables, contains as much 

 azote and ammonia, and is as putrescent, as that of a man Jiving on ani- 

 mal food ? Respiration does not introduce a single particle of azote in our 

 fluids; this gas comes out of the lungs as Unentered ; the oxygen alone is 

 diminished in quantity. Might not one suspect that this element of ani- 

 mal substances is a product of the vital action, and that instead of re- 

 ceiving it from our aliments; we form it within ourselves, by an act that 

 is hijjicr-chemical; that is, which chemistry cannot imitate J ? 



CXI. It has been maintained, that the hydro-carbonous oxide, com- 

 "bines, in the stomach and intestinal canal with oxygen, whether this last 

 principle has entered, with the aliments, into the digestive tube, or whe- 

 ther it is furnished by the decomposition of the fluids within that cavity. 



* See the Jlnnales tls CMnue, a^d the Systtme des Connaissances Cfdmiqnes cle Four- 

 croy. Tome X. page 7'2. 



j- The late experiments of Messrs. Allen and I'cpys prove, that when an animal is 

 made to breathe pure oxygen, the blood disengages a certain quantity of azote, and ab- 

 sorbs an equal quantity of oxygen. Philosophical Transactions, 1809 Copland. 



\ The question asked by the author is not philosophical. Either the elements of azote 

 must be furnished by the 'aliment or atmosphere, or else the azote itself must thus be 

 introduced. Otherwise we must admit that the vital power can create, azote without 

 materials, or from nothing, which is-absurd. Godmpn. 



