The Bolivar bulletin. [volume] (Bolivar, Hardeman County, Tenn.) 1865-1888, 1883-03-15
Soaps.

By fne term soap is commonly under
stood the various commercial products
obtained by the action Of caust c
alkalies on the fixed oils and fats. The
soaps of commerce are divide broadly
into two classes-hard and soft. Hard
soaps are made with solid animal fats
or vegeta lie fat oils and soda; for SO t
soaps, fish oils or vegetable driving oils
are used, saponification being effected
with potash. Hard SCARS may be OBJ
tanned with potash. provided a solid fat
be employed, but a potash soap is al
ways softer than soda soap produced
from the same fat. The hard soaps
usually consist essentially of the sod
salts of the fatty and resin acids of the
materia's s, the excess of alkaG and the
glycerine having ben 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 granulaE Ons, 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 granulat.On, COM
monty but Improperly regarded as q
proof of quality, it is sometimes initiated
by an admiXture of starch. Marine
soap is made partially or wholly from
cOcOanut or palm nut oil, which contains
glycerides of the lower fatty acids
Cold water soap usually contains aka
Line carbonates. Such soap fathers toll
erably well 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 deIiques-
D0tb ,,Oforh .nI cnHo
readily soluble in hot water and alcO-
hOl; their concentrated solution. sOlidi-
fies to a Jelly on cooling. OpodeIdoc is
this jellied soap mixed with alcohol
COpiOus dilutiOn OF a solution of soap
with cold water or the cool No of hot
dilute solution. causes precipitation o.
acid stearate and palmitate, while free
alkali remains in solution. 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 base present b, is greater in pro-
portion to the stearine and almitine
pre-existent in the oil, and less in pro
portion to the olein in it. Soda soaps
are soluble in water, but insOluble in
brine and other strong saline solutions.
When a 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 Gaps are
thrown down. Pc ash soap can not
be separated in a 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 a
s da soap, an e uivalent amount of
chloride of potassium being formed i'll
/ ,e
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-nutoi soaps require a much larger
| proportion of salt to separate them from
! their solutions than is the case w tn any
other varieties. Hence their use on
! board ships, as they form a lather with
ca water. These {. Is require a much
| stronger alkaline I've for their sapOnifi-
| alton than is the case with other oils.
! The accurate determination of the wa
| ter of soap re 1uirCs considerable care
! If the soap be a sold one fairly repre-
| sentative sample shou'd be reduC ed to
! fine shavings by scraping wi. h a knife.
! A known weight is then exposed for
some time to tempera, o forty CT
! fifty degrees cent;grade, 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 notGe allowed
to II cit. A better metT Cd is to dissolve
about two grammes OF soap in the mini
n um quantity of hot strong alcohol and
| to pour the liquid on a known EIGHT of
! clean dry sand, which is then exposed
with frequent stirring to a temperature
of 10 degrees centigrade. 7 he water
| in soap may also be eStima ed by differ
ence. CLOtIleT and FIlni5ber.