fSeptI> 
156 
Anahjsis of VegeAahtes and Animats. 
performed upon 2 or 300 times less matter 
ifan the'latter. This is, because in the 
former, where we judge of weights by 
•volmnes which are very considerable, the 
errors wiiich we may commit are perhaps 
1000 or 1200 times less perceptible than 
dn the latter, where we are deprived of 
this resource. Noiv,'as we transform 
into gas the substances which we ana- 
Ivse, we bring our analyses not only to 
the certainty of the common analyses, 
but^to that of the most precise mineral 
analyses; more particularly as we collect 
at least a litre of gas, and as we find, even 
in our way of proceeding, the proof of an 
extreme exactitude, and of the most tri¬ 
fling errors. 
We have already methodically ana¬ 
lysed, with all the precautions just men¬ 
tioned, sixteen vegetable substances; 
Tiir, tlie oxalic, tartarous, mucous, citric, 
and acetic, acids; turpentine in resin; 
copal, w’ax, olive oil, sugar, gum, starch, 
sugar of milk, oak, and aslnwood, and 
die chrystallisable principle of ’manna. 
The results which w'e obtained, seem to 
ns to be of the first-rate importance, for 
they led to three very remarkable laws to 
wiiich the composition ofvegetables is sub¬ 
jected, and which may be thus expressed: 
’Etral Law.-’-A vegetable substance is 
Aittays acid when the oxygen is io the hy¬ 
drogen in a g7'€ater yroporiion than in 
water, ("85 io 15,} 
Second Lato,—A vegetable substance jV 
always resinouSy. oily, or alcoholic, 4’C, 
when the oxy^^co- in a less pj'oportion to 
the hydrogen than in zcater. 
Third Law, — Lastly, a vegetable sub¬ 
stance is neither odd nor resinous, and is 
analogous to s^gdv, gum, starch, sugar of 
milk, to the ti^neeus fibre^ to the chrys- 
tallisahle principle of manna when the 
oxygen is in the same proportion as in 
water. 
Thus, supposing fof u moment that hy¬ 
drogen and oxytren were in the state of 
water .in vegetable substances, vvhich 
we are fiir fronv thinking is the case, 
the vegetable adds would be formed of 
carbon, water, and oxygen, in Various pro^ 
portions. 
The resins, the fixed and volatile oil^, 
alcohol and ether, vvould be Formed of 
carbon, water, and hydrogen, also in va¬ 
rious pi'oportions. 
Lastly, sugar, gum, starch, sugar of 
milk, the ligneous fibre, the chrystttlliza- 
ble principle of manna, would only be 
formed of carbon and zoater, and would 
only differ in the greater or less quantities 
which they contained.* 
This may be shewn by citing various 
analyses of acid and resinous substances, 
and of substances which are neither acid 
nor resinous. 
One hundred parts of oxalic acid contain; 
Carbon .... 2^566'^ ['oxv.gen and hydrogen in the proportions in which 
Oxygen .... -£ J ""they exist in water. 
HjdrQS=n Oxygen m excess ... 
100 J o 
One hundred parts of acetic aeid contain : / 
Carbon _50.2241 ^ j^Carbon ./-• -.* V V 
Oxvgen 44*147 ^ Ozygen and hydrogen in the proportions m which 
jh ^ con i T ; they exist in water... 
Bydrogen o 629 ^ • 
■' ® __ r Oxygen rn excess__ — .. 
~ iT I 
100 j C . 
25-566 
22 872 
50*562 
100 
50 224 
46 911 
2-865 
100 
The oxalic acid contains, therefore, 
more than half its weight of oxygen in 
excess, in piroportion to the hydrogen, 
whereas in the acetic acid this excess is 
jiot quite three centiemes. 
These two acids occupy the extremes 
of the series of the vegetable acids: of 
all the acids the one is the most, and the 
other is on the contrary the least, oxyge¬ 
nated: this is the reason why it requires 
so much nitric acid to convert su^ar and 
O 
gum, ccc. into oxalic acid; and this is the 
reason, on the contrary, that so many 
vegetable and animal substances produce 
so easily acetic acid, in a great many cir¬ 
cumstances, and that wine, in particular, 
is changed into vinegar vfithout any in<- 
termediate acid being formed; a phe¬ 
nomenon which had not been hitherto 
explained, because vinegar has been re¬ 
garded as the most fiighly oxygenated of 
all the acids. 
* There is a striking coincidence between 
these interesting results, and the principle 
stated in Art, 2d, at page 117, of the present 
number. 
Onf 
