The Redwood gazette. [volume] (Redwood Falls, Minn.) 1873-1940, 1876-07-13
The Manufacture Of Glucose.

AS there is just now much inquiry as to
the process of making glucose, or grape
sugar directly from starch or other vegeta-
Die matter, the following will be Of in
terest:
Dilute sulphuric acid and the fecula of
the potato are the active agents in the pro-
ductlOn OF grape sugar from starch. The
principal processes are the following: The
boiling of starch meal with dilute sui
phuric acid is effected on small scale in
leaden pans; but in an extensive prepara-
ton, iron pans are employed. The requi-
site quantity of water is first heated to the
boiling point, and to this is added the sui
phuric acid diluted with three parts by
weight of water. The starch is also
brought, by the addition of water, to a
milky consistence. The liquids SO pre-
pared are mixed, and the boiling contin-
ued until all the starch is converted into
sugar. An intermediate stage, not usually
noticed by the manufacturer, is the con-
version of the starch into dextrin, which,
in its turn, suffers conversion into sugar.
The entire conversion of the dcxtriu into
grape sugar cannot be with certainty as
certained by the iodine test, as sometimes
| purple-red tint is produced, while in
others there is no change. The most reli-
able test is that with alcohol, founded on
the well-known insolubility of dextrin in
an alcoholic menstruum. If no precipi-
tate is thrown down there is no dcxtrin re-
naming, and the conversion has been en-
tire. The proportions of materials are,
generally, to 200 pounds of starch, four
pounds of ordinary sulphuric acid of sixty
degrees Baumc, and from eighty to one
hundred gallons of water. The con-
version of the starch and grape sugar
is fastened by the addition of small
quantity of nitric acid The separation
of the sulphuric acid from the sugar solu-
ton is most important operation, for the
color, purity and flavor all depend upon
success in this stage of the process. The
acid is neutralized with baryta or lime,
with either of which it forms an insoluble
salt, deposited at the bottom of the neu-
tralization vessels, and leaving clear SUI
pernatant sirup. The baryta can be en-
ployed as carbonate (withcritc), and is,
without doubt, the better neutraliZipg
agent, sulphate of baryta being very in
soluble. Lime, although ordinarily used,
forms with the sulphuric acid sulphatc
(gypsum) that is not perfectly insolublc
in water. 1t can be employed as marble
dust, chalk, or caustic lime. The neu
tralization is completed in the boiling pan
while the sirup is still hot. For every
pound of sulphuric acid so much pulver-
lied marble is required as the varying
strength of the acid may demand, about
pound to pound. After the addition Of
the marble powder, and when the ctfcr
vescencc has subsidized, the liquid must be
tested with litmus paper, or better, with
tincturc of litmus; if the sugar solution
be neutralized when at twenty-six degrees
Baumc density, the following evaporation
will concentrate even the smallest quantity
of sulphuric acid which may have re-
NAMED, and rendered another neutraliza-
ton necessary. To insure perfect ncu-
tralization, it is useful to add an excess
of carbonate of baryta in the proportion
of five to ten ounces to every ten pounds of
sulphuric acid. The evaporation and pu-
riication are similar to these employed
for other SurarS =Scientifc dncric0n