A Manual of the Chemistry of the Carbon Compounds

888 THE CHEMISTRY OF
A small quantity of sugar is at the same time converted into other
products; about 2-5 per cent, being transformed into glycerin and
0-6 to 0-7 into succinic acid.
The yeast which is formed in the fermentation of the juice of grape
and other kinds of fruit, and of malt-wort, is produced from soluble
albuminous bodies contained in fruit and corn. It consists of one of
the lowest members of the vegetable kingdom (Tontla cerevisim), and
under the microscope is seen to be made up of little oval, transparent
globules, having a diameter of not more than O'l mm,, and often
cohering in clusters and strings. They are propagated by budding,
and quickly die as soon as they have reached their highest state of
development. In contact with air aud water, yeast soon undergoes
putrefaction.
Lactic Fermentation.—This kind of fermentation takes place by
adding putrefying cheese to a dilute solution of glucoses, cane-sugar,
milk-sugar, or gum, and exposing it to a temperature of 25° to 35°,
C6H12Oe . 2C8H6O8
Acids prevent lactic fermentation, and therefore chalk or zino
oxide is added to keep the.solution neutral. Together with lactio
acid, a certain quantity of mannite is always produced, and also a
peculiar microscopic fungus consisting of smell globules.
Butyric Fermentation.—When the semi-solid mass of calcium
lactate formed in lactic fermentation is exposed to a temperature
above 36°, it redissolves, being converted into soluble oaloium butyxate.
At the same time hydrogen is evolved, and a living microsoopic
organism having a cylindrical shape and a length of about
making its 0-02 mm. appears in the liquid.
Mueie Fermentation..—-Under certain conditions which aTe not quite
understood, dextrose undergoes mucio fermentation, the products of
which consist of lactio acid, mannite and a kind of gum; a microscopic
fungus in the shape of small globules, adhering in rings,
making its appearance at the same time.
Other kinds of fermentation will be found under the head of
Glucosides.
TERPENES AND CAMPHORS.
This group consists of a number of compounds, containing ten
atoms of oarbons in the molecule. The terpenes are hydrocarbons,
having the common formula CiaH1?, and possessing very similar chemical
properties, whilst their physical properties vary; the different
compounds having different boiling-points, specifio gravities, &c.
Their odour also varies much, and most of them are optically active;
some turning the place of polarization to the right, others to the left.
The cause of this physical isoxaemm is not yet known.