The Manitowoc pilot. [volume] (Manitowoc, Wis.) 1859-1932, 1907-07-11
THE Markings OF GLUE.
Not a Definite Organic Substance, But
Product of Several Transformations.

Glue is not a definite positive organic
substance as most people suppose.
Chemists tell us that glue does not pre-
exist in any animal organism except un.
der abnormal condltions-aS in disease
but is the product of several TRANSFORMED
tons.
The first transformation takes place
in drying the hide. If the green hide is
boiled after being prepared in exactly
the same manner by lining, etc, while
it is yet green, an entirely different prod
uct Of less consistency is secured than by
drying the hide after lining and then
boiling.
The second transformation seems to
take place in boiling the material, prob
ably from action of the heat. The third
transformation occurs in the drying of
the jelly secured i'll the boiling opera
ton.
Still another transformation occurs in
the drying of this jelly into actual glue,
and this series of changes does not end
here, for glue dissolved in water and
again boiled sufficiently long loses its
form once more and will not gelatinize,
but will remain in liquid form.
Glue yielding substances are produced
by the animal economy from proteine
bodies. albumen, tbrne and caseine.
The impossibility of preserving for any
length of time the stock from which
glue is made renders it necessary to
adopt some system in choosing and pre-
serving it until sufficient quantities are
collected without fermentation or de-
compositions Hence the refuse from tan
neries consisting of the clippings of
hides. ear and tail pieces Of OK, calf and
sheep. and from skins Of other animals
are preferred. because they can be
dressed with lime, which removes the
hair and acts as an antlSCptlC.
The ordinary bone stock glue is made
from the larger bones of cattle and horn
piths. collected from different sources. 4
large quantity of waste bones is accumu-
lated in the preparation of timed pro-
visions
If these have not been overheated and
are in good condition considerable
amount of glue can be obtained from
them. The bones from the head. ribs
and feet give a better yield than those
of the thighs and legs.
There is also the hoOf glue, which is
made from the hoofs of different ami
mails. Then there is glue made from
sinews and fcshinEs, aud also grade
known as rabbit glue made from the
skins of hares and rabbits. This glue
makes a good water test, but should
never be used to cement belt. There is
a large quantity of this glue made in this
country, and a person not very familiar
with it could EARLY be deceived.
The age of animals yielding glue stock
has an important influence on the prod
uct While from Younger animals the
production, as a rule. is of a lighter col
or more abundant, and more easily OBJ
tanned. il contains more chOndrin, so that
for solutions of equal strength those
from mature animals will be found to be
of the greater consistency and the glue
more solid
Then, again. there is what is known as
the pig stock glue, which is made from
the feet of hogs. Next comes the fish
Glue or isinglass. Its varieties are nu
merous. and thorough knowledge of
them can only be obtained when one is
personally acquainted with the different
factories and stock from which they are
made
The best of this material however, is
made from the sounds or air bladders of
the different species of fish. The air
bladders of the common sturgeon and
other fish caught in northerly climates
makes the best.--Wood Craft.