155- 
1 Si 1*1 Analysis of Vegetables and Animals 
iiyper-oxygenated muriate; quantities of take sortie precautions in order that the 
both are to be.weiglied in very accurate stop-cock may not be heated. With this 
scales; they are to be well mixed, moist- view th|e glass tube is passed through a 
ened, and rolled into cylintlers; these brick, to which it is fastened with clay, 
are to be divided into small balls, which and which at tiie same time gives solidity 
are to be exposed to a boilutg heat in to the apparatus: besides this, w'e must 
order to render them as dry'^3 the ongi- solder to the body of the stop-cock a 
nal materials were. Il the substance to small hollow cylinder, in which water is 
be analysed is a vegetable acid, it is to put, or rather ica. 
be combined with lime or barytes before We have thus all the necessary data 
mixing it with the hyper-oxygenaied ran- for knowing the proportion of the prin- 
r.aie; the salt which results is to be ana- ciples of the vegetable substance: we 
lysed, and an account is to be taken of know how much of tliis substance has 
t-he carbonic acid wln'ch remains united been burnt, since we have the weight of 
to the base after the experiment: lastly, it to a demi-miliigramme': we know ijovr 
if the substance to' be analysed contains much oxygen is wanted to transform it 
some bodies which are, foreign to its na- into water and into carbonic acid, sine® 
ture, they are also to be taken account of. the quantity of it is given by the differ- 
Thus we know accurately that a given ence which exists between that contained 
weightof'thrs mixture represents a known in the hyper-oxygenated muriate, and 
weight of hyper-oxygenated muriate, and that contained in the gases; lastly, we 
of the substance which we vvish to ana- know how much carbonic acid is formed, 
lyse. and we calculate how much water oughg 
Now, in order to finish the operation, to be formed, 
nothing more is requisite than to make By following the same order of analy* 
the bottom of the tube red hot ; to drive sis, we also succeeded in determining 
off all the air by means of a certain iium- the proportion of the constituent princi- 
ber of balls, which we do not weigh, and pies of all the animal substances. But, 
which we throw in one after another; as these substances contain azote, and 
then to decompose in the same manner as there would be a formation of nitrous, 
a. weight of them precisely determined, acid gas, if we employed an excess of 
and carefully to coll^ect all the gases in hyper-oxygenated muriate in order 
flasks full of mercury, and gauged before- burn them, we,need only employ a quan*« 
hand. ■ tity suificient for reducing them com" 
If all the flasks are of the same capa- pletely into carbonic acid gas, oxy-car- 
city, they will be filled with gas by equal buretted hydrogen, and azote, of wiiich 
weights of mixture; and if we examine w-e perform the analysis in the eudioineiei’ 
these gases, we shall find them perfectly vvith mercury by the common methods, 
identical, an evident proof of the extreme and from which we may conclude exactly 
accuracy of this method of anaiysis. that of the animal substance itself. 
The tube ought to be kept oaring tlio Tiie meth'od in which we proceed to 
whole operation at the highest degree of the analysis of vegetable and-animal sub¬ 
heat which it can support without melt-, stances being exactly known, we can 
ing, in order that the gases may not con- tell what quantity of it we decompose 
tain any ox-ycarburelted hydrogen gas. without any fear of weakening the coii- 
In all cases the analysis oueht to be per- fidence whicli we ought to have in our 
formed over mercury. I’his is a proof results. This quantity rises, at most, to 
to which it is indispensable to subject six decigrammes; besides, if there was 
them: for this purpose it is sufficient to the smallest doubt us to ilieir exactness^ 
mix them with one-fourtli of their volume we could get rid of it upon recoliecting, 
of hydrogen, and to pass an electric spark tjiat we fill successively with gas two 
into them. As they contain a great ex- and sometimes tlirec flasks of the same 
cess of oxygen, the hydrogen w hich we capacity, that these gases are icieaticai, 
add, and -of which an account must-be and always proceed from une and the 
kept, burns as well as the whole oxy-car- same weight of inaterials. 
buretted hydrogen, which they may con- We might add, that the exactness of 
tain; and we thus acquire the certainty any analysis consists rather in thb accu- 
that they are no longer formed of any racy of tfie instruments, and of die me- 
thing but carbonic acid and oxygen, thodswhichweempIoy,thaninthequan- 
which must be separated by potash. - tity of matter upon which we operatp. 
But this necessity of raising the tern- The aitalysisof the air is more exact than 
pexature obliges us on the other hand to any analysis of the salts, and yet it is 
performed 
