The Iola register. [volume] (Iola, Allen County, Kansas) 1875-1902, 1883-03-16
Soaps.

By the term soap is commonly under
stood the various commercial products
obtained by the action of caust 9
alkalies ON the Fl ed OILS and fats The
soaps of commerce are divide l broadly
into two classes-hard and soft. Hard
soaps are made with solid animal fats
or vegeta lie fat oils and soda; for so
soaps, fish oils or vegetable drying oils
are used, saponification being effected
with potash. Hard SOAPS may be OBJ
tanned with potash, provided solid fat
be employed. but potash soap is al
ways softer than a soda soap produced
from the same fat. The hard soaps
usually consist essentially of the soda
salts of the fatty and resin acids of the
materials. the excess of alkali and the
glycerine having been separated; but
in the case of soft soaps no such separa-
ton is attempted. the whole being
boiled down together. Hence soft
soaps are more caustic than hard
soaps and contain various impurities.
The solid white granulations, often seen
in soft soap. consist of potassium
stearate, and to produce them a small
quantity of tallow is used in the manu-
facture. As to the granulation. COM
monty but Improperly regarded as
proof of quality. it is sometimes initiated
by an admixture of starch. Marine
soap is made partially or wholly from
cocoanut OF palm nut oil. which contains
glycerides of the lower fatty acids.
Cold water soap usually contains aka
line carbonates. Such soap fathers toll
erably wei with hard water. Soda
soaps are mostly solid and hard at the
ordinary temperature and in the alb.
sence Of free a kali are not deliques-
cent. Both potash and soda soa are
readily soluble in hot water and alcO-
hol; their concentrated solution sOlidi-
fies to jelly on cooling. Opodeldoc is
this jellied soap mixed with alcohol.
Copious dilution of solution of soap
with cold water or the G. oil NJ of a hot
dilute solution causes pre- .ipitatiQn OF
acid stearate and palmitate, while free
alkali remains in solut on. 1t is proba
bly, to this reaction that the detergent
properties of soap are due. The hard.
ness of soap is not de endent solely on
the Ease present b, Is greater in pro.
portion to the stearine and lalmitine
pre-existent in the oil, and less in pro.
portion to the olein in il. Soda soaps
are soluble in water. but insoluble in
brine and other strong saline solutions.
When moderately strong solution OF
hard soap is precipitated by addition
of common salt the compositions of the
separated soap is unchanged. but from
very dilute solutions acid soaps are
thrown down. Pc ash soap can not
be separated in similar manner
by adding chloride of potassium
to its solution. If common salt be
added to the solution of potash
soap the precipitate consists of
81 da soap, an uivalent amount of
chloride of potassium being formed in
the solution. Concentrated solutions of
caustic and carbonated alkalis also
separate either potash or soda soap from
its SO ution, but in weak alkaline Ives.
soap is readily soluble. Cocoanut and
palm-nut oil soaps require much larger
proportion of salt to separate them from
their solutions than is the case W tn anv
other varieties. Hence their use on
board ships. as they form lather with
sea water. These o Is require much
stronger alkaline I've for their saponiti-
alton than is the case with other oils.
The accurate determination of the wa
ter of soap requires considerable care.
If the soap be a so id one fairly repre-
sent atire sample shou d be redu" ed to
fine shavings by scraping with knife.
A Known weight is then exposed for
some time to a temperature o. forty or
fifty degrees centigrade, the heat being
gradually raised to 100 degrees cent?
grade. and continued at that tempera-
ture as long as loss of weight is OBJ
served. The soap should not e allowed
TO melt. A better method is to dissolve
about two grammes OF soap in the mini
n um quantity of hot strong alcohol and
to pour the liquid on known weight of
clean dry sand. which is then exposed
with frequent stirring to a temperature
of lilo degrees centigrade. The water
in soap may also be estima' ed by diter-
ence.-Ckothter and Furnisher.