ceives its name from its resemblance to a prineiple of animal matt ™ 
It is soluble in cold water, its solution being coagulated by heat or 
by alcohol ; it is liable to putrefaction, and furnishes a large quan- 
tity of ammonia on exposure to heat. It abounds in the eS 01 
several acrid and narcotic plants, and is also contained in the gra- 
mineous seeds. 
» Saccnarine MaTrer.—This exists in many vegetables, particu- 
larly in their fruits and roots, generally united with their gum and 
extractive matter. When pure its taste is sweet. It is soluble in 
water and in alcohol ; is capable of crystallization. By fermenta- 
tion, it is converted into alcohol, as this, by a second stage of fer-_ 
mentation, it is changed into acetous acid. By the action of ni- 
trous acid, it is converted into oxalic acid. By decomposition by 
heat, it affords more than half its weight of acetous acid; a small 
quantity of empyreumatic oil, carbonic acid, and hydro-carbonate 
gases, the residuum being charcoal. It consists of oxygen, carbon, 
and hydrogen. : 
Essential saLts.—The saline substances contained in vegeta- 
bles have been termed their essential salts. They are either acids 
here are seven acids found native in vegetables ; the mal 
citric, oxalic, gallic, tartarous, acetous, and benzoic. The first five _ 
consist of carbon and hydrogen, brought to the state of an acid by 
oxygen, and differ from each other chiefly in the proportion of hy- 
drogen and carbon they contain. (ee 2 
_ The oxalic acid contains the largest proportion of oxygen ; and 
it is into it that several of the other acids, and many of the vegetable 
oxyds, are converted by oxydation. It is very soluble in water, and- 
erystallizable. It is distinguished by the very strong attraction which 
it has for lime, which it takes from every other acid. As it exists 
in vegetables, it is commonly united with potash, but so that the 
acid is present in excess. ae 
_ The malic acid is contained in apples and in many other fruits be- 
fore they are ripe. It does not crystallize; it contains more oxygen — 
than the citric acid does, and is converted into the oxalic acid by the 
action of the nitrous acid. «=~ ia Seas ies 
. The citric acid is soluble in water and crystallizable; it has a 
stronger attraction to the earths than to the alkalies ; it is not, like the 
malic, convertible into oxalic acid. 
The tartarous acid, as it exists in vegetables, is generally com- 
bined with potash, but in such a quantity as still to leave an excess — 
of acid. From this salt the pure acid of tartar. is obtained ; it is 
very soluble in water, and is crystallizable; it is convertible into 
oxalic acid; it is decomposed by heat, and affords more empyreu- 
matic oil than any of the other acids; henee, it has been inferred, 
that it contains a larger proportion of hydrogen. 
- ‘The acetous acid, though generally the product of fermen 
has been found in the sap of the vine, and in some other v 
It is de osed: in a high temperature, and along with 
