A Manual of the Chemistry of the Carbon Compounds

THE CARBON COMPOUNDS. 405
Its alkaline solution may be boiled without being changed.
Sulphuric acid dissolves hsematin, and on adding water, the compound
C34H80N4O9 is precipitated; it is an amorphous mass resembling
hsematin.
ffcmatin Hydrochttyi'ide or Hasmine (C8,HMN^O6Fe)j!(HCl)3 is produced
by heating hwmttglobin with glacial acetic acid, and common,
salt. It crystallizes in thin rhombic plates, possessing a brownishred
colour, and bluish-red reflection. Alkalis decompose it into
hsematin and hydrochloric acid.
The formation of these blood-crystals is made use of as a test for
detecting blood-spots in criminal cases.
Mutin is contained in the secretions of the mucous membranes
and is conveniently prepared by precipitating filtered cx-bile with
alcohol, dissolving the precipitate in water, and precipitating again
with acetic acid. It swells up in a little water, and dissolves in a
large quantity ; its solution does not coagulate on heating. Mucin
contains: carbon 52*2, hydrogen 7*0, nitrogen 12*6, oxygen 28*2.
Keratriti.—TMs, name is given to the residual mass, which is
obtained by exhausting epidermis, nails, claws, hoofs, hair, wool,
-whale-bone, &c, with ether, alcohol and a dilute acid. It dissolves
in potash with the formation of ammonia and potassium sulphide,
and acids produce in this solution a gelatinous precipitate. When
the substances above mentioned are boiled with dilute sulphuric acid,
they yield tyrosine and leucine, and nitric acid imparts to them a
yellow colour, The composition of keratrin does not differ much
from that of the proteids, but it contains more sulphur:—
Poreentago of
Sulphur.
Human-hair . . . . 4—5
Human-nails . . . . 2-8
Epidermis 0*7
Wool 2—3-5
Horse^hoofs . . . , 4*2
Whale-bono . . . . 3*5
Tortoise-shell.... 2*0
Elastiii ia a substance resembling keratrin, and is contained iu the
ligammtmn, ntichas of cattle. It is in the moist state extensible, but
becomes brittle after drying. Its alkaline solution is not precipitated
by acids. A similar substance has been found in the egg of the
common snake.
GELATIN AND CHONBEIN.
These twc compounds do not pre-exist in the animal organism,
But are produced by the action of boiling water on certain tissues.
Gelatin is obtained by boiling bones, tendons, skin, bladder, &c.,