64 On VegciaUe and Animul Anal ysis^. 



muriate in order to burn lliem, we need only employ a 

 qiiantitv siifTicicnt tor reducine; tlicni coiuplettly into car- 

 bonic acid gas, oxy carbiirelted liydrogin, and azote, of 

 which we periorni the analysis in the eudiometer with mer- 

 cury bv the common methods, and from which we may 

 conckide exactly that of the animal substance itseU". 



The method in which wc proceed to the analysis of ve- 

 getable and animal substances being exactly known, we 

 can'tell what qiiantitv nf it \^'e dtcompose without any fear 

 of weakening the confidence winch. we ought to have in 

 our results. This quantity rises at niost to six decigranmies : 

 befides, if there was the smallest doubt as to their exactness, 

 we could get rid of it upon jecollcctintr ihat we till suc- 

 cessively with gas, two nnd sonutimes tliree flasks of the 

 same capacity; that these gases arc identical, and always 

 proceed from one and the same weight of materials. 



We might add, that the exactness of any analysis consists 

 rather in the accuracy of the instrument?, and of the me- 

 thods which weemplov, than in tlie quantity of matter upon 

 which we operate. The analysis of ihe air is more exact 

 than anv analysis of the salts, and yet it is pertbrmed upon 

 2 or 300 times less matter than the latter. TI:is is because 

 in the former, where we judge of weights by volumes which 

 are very considerable, the errors which we may commit are, 

 perhaps 1000 or 1200 times less perceptible than in the 

 latter, where we are deprived of this resource. Now as we 

 transform into gas the substances which we analN'se, we 

 bring our analvses not only to the ceriainty of the com- 

 mon mineral analvses, but to that of the most precise mi- 

 neral analyses; n)ore particulnrly as we collect at least a 

 litre of gas, and as we find even in our wav of proceeding 

 the proof of an extreme -exactitude and ol the must trifhng 

 errors. 



We have already metlio^icallv analysed, with all ihe pre- 

 cautions just mentioned, sixticn vegetable ?ubstances; \\z. 

 the oxalic, tartarous, mncou^, ciiric and arctic acids; tur- 

 ])entine in resin; copal, wax, olive oil ; sugar, gum, starch, 

 suffar of milk, oak and ash wood, and the ciystaluzable 

 principle of manna. The results which we obtained seem 

 to us to l)e of the first rate importance, for tlu-y led to three 

 very remarkable laws lo which the composition of vegeta- 

 bles is subjected, an<l which may be thus expressed: 



FinsT Law. — A vegetable substance is alway* acid when 

 the oxxiien i ; to the hydrogen in a greater proportion than 

 in water. 



Si.coND Law. - A vegetable Slabs^tance is alw ays resinous, 



ody, 



