A Manual of the Chemistry of the Carbon Compounds

THE CARBON COMPOUND*}. 497
By treating sponge with ether, alcohol, hydrochloric acid, and
dilute soda, spcmgin is left behind, which has great resemblance to
fibroin, and also yields glyeocol, and leucine, but no tyrosine.
S&ricin or SiM-gelatin C|BH^N608 is a substance resembling
gelatin. Its hot aqueous solution is precipitated by alcohol, and after
drying the precipitate forms a colourless powder, which in cold
water swells up to a gelatinous mass. On boiling it with a dilute
sulphuric acid it yields a small quantity of leucine, and larger
quantities of tyrosin e, and serine, or amidoglycerie acid.
FERMENTS.
Under the head of fermentation it lias already been mentioned
that several kinds of sugar, and other bodies such as glucosides,
if a ferment be added to their dilute solution, are resolved into
two or more new compounds. Ferments are proteids in a peculiar
state of decomposition. Their constitution is quite unknown, and
none of them has been yet obtained in a pure state,
Yeast consists of one of the lowest members of the vegetable
kingdom (Torula ccrevisw). On treating it with dilute potash the
cells are disintegrated, and their contents dissolve in the potash. On
adding acetic acid, white flakes are precipitated, which, after drying
form a yellow, brittle mass, and contain :—
Carbon 55*0
Hydrogen 7*5
Nitrogen 14-0
Oxygen 230
Sulphur . . . . . . 0-5
100-0
Yeast has not only the property of resolving glucose into alcohol
and carbon dioxide, but also to decompose calcium inalate into
calcium carbonate, acetate and succinate, and to convert salicin in
presence of chalc, into lactic acid, and saligenin.
When yeast is kept under water, fermentation sets in, carbon
dioxide is evolved, and the liquid contains after some tune a little
alcohol, a kind of albumin and leucine.
By washing yeast with water, an organic substance goes gradually
in solution, possessing in the highest degree the property of converting
cane-sugai into inverted sugar.
Diastase.—When grain germinates a portion of one of the proteids
is transformed into diastase, which may be obtained by precipitating
a cold infusion of malt with alcohol in white flakes. Its aqueous
solution is not coagulated on heating, and possesses the properties of
converting starch into dextrin and dextrose, one part being sufficient
O K K