The Sun.
London, England, 1859-11-10 00:00:00

SOAP.

By Sheridan Muspratt, Esq., M.D., F.R.S., Edin-
burgh, &T.; Professor of Chemistry, Liverpool.
Health and economy are the leading desiderata in
our conventional system of society, and there is no
substance presenting more important relations to
that plan, and to domestic comfort and cleanliness,
than soap. Though a luxury, it is condered a prime
necessity of life throughout the civilised world.
Rich and poor alike appreciate its usefulness, so
that the annual quantity consumed amounts to
hundreds of millions of pounds. In this country the
average consumption is 71bs. per annum for each
person, and in the United States something less, of
which latter ratio, however, about one-sixteenth
consists of imported fine soaps, including Castille
and toilet soaps. In Jamaica the ratio is slbs. per
head annually. The figure, however, in none of
these instances, is as high as the usual allowance in
alms-houses, particularly in England, where it
amounts to 101bs. for each inmate.
Chemically considered, soap is a definite com-
pound if one or more of the fatty acids, with a
metallic, earthy, or alkaline basis. Tire metallic
soaps, called also plasters, are only known in
pharmacy. The earthy saponaceous bodies have
no practical application, and, like the preceding,
are insoluble in water.
The alkaline soaps, on the contrary, dissolve
readily in that fluid, and are characterised by the
property of detergence.
This cleansing power gives them great practical
value and importance, for by this means water is
made to dissolve and remove greasy dirt from the
skin and garments, and it is for washing these that
soap is principally used. Soap is distinguished as
hard or soft according to its basic character ; soda
being the base of the former and potassa of the
latter.
The term soap is derived from the Latin word
sap, a corruption of the German sepe, now written
seife. The Hebrews,Egyptians, and Greeks in ancient
times NN rshed their clothes with free alkali ; but
according to Pliny, soap originated with the Gauls,
and thence the knowledge of the art of making it
passed to the Germans, and probably extended from
them to the Romans.
A complete soap factory exists in the ruins of
Pompeii, destroyed by an eruption from Vesuvius in
the first Christian century.
The art was known in France during the eighth
century, as history mentions that a soap maker
formed one of the domestic corps of Charlemagne.
In England it is probably about the year 1,500,
it was first known, but the earliest authentic record
is in 1641, the date of a small brochure on the soap
business now in the British Museum. Soap was
made in 1710, during the reign of Queen Anne, with
fat, ashes, and salt, very much after the present mode
of working with these materials. The manufacture
of soap is eminently a chemical art, but it has
been mostly in the hands of the ignorant, and,
eonsequenty, its progress has not kept pace with
discovery in applied science.
Nearly all the improvements which have been
made—even those pertaining to the practical de-
tail of the art—owe their origin to men of study.
I Indeed, such has been the inveterate devotion of
mere working men in this business to old ways,
old imperfections, old errors and prejudices, that
nothing less than the loss encountered by them
in the competition with those who more wisely
adopted the plan of scientific workers has ever
induced them—and even then but tardily—to
follow the lead of their more successful fellow-
labourers. It is a curious incident in the history
of blind devotion in the trades of old recipes,
&c., that the writer's father, after essaying for
a long time in vain, by reasoning, to induce the
soap manufacturers to employ the better and more
economical soda ash as a substitute for wood ashes,
barilla, and kelp, was obliged, from a pride of
science and a desire to benefit the groping labourer,
to gratuitously send his loads of alkali and empty
them at the very doors of the workmen.
Chevreal cast the first great light upon the dark-
ness of the way, in 1811, by his discovery of the
compound nature of fats, and a few years earlier
Leblanc made a valuable contribution of a ready
process for making soda artificially from common
salt. In more recent times Tilghman has improved
upon this latter benefit by producing the alkali at
the time of manufacture in a caustic state, without
the necessity of de-carbonating it with lime. Still
later Morfit, of New York, has devised a new and
eftTcient boiling apparatus, by which the soap is
made with great promptness and of unvarying
uniformity in appearance and composition. This
same chemist has within the last year added further
to our knowledge of the subject, by giving a method
for utilising red oil—crude oleic acid—as a fat stock
for soaps of a superior quality. The plan is
patented, and promises to produce a reform in the
present mode of making the first grades of bath
and laundry soaps.
The high value of fat stock often leads to the de-
basement of the quality of the laundry soaps for
the purpose of reducing their cost price. Tea to
twenty per cent. of rosin are admissible for the ob -
ject, as that substance, when combined with alkali,
assists the detergent power of the soap in a limited
degree. But beyond that proportion it injures it,
so also any other of the substances now so fre-
quently employed, such as clay and the like, as a
mere cheapening or defrauding mixture which de-
tracts muca from, without adding in the least to,
the value of the soaps.
College of Chemistry, Liverpool,
Nov. 7, 1859.

THE PADDLE, SCREW, AND PUMP.—Many dis-
putes have a' isen as to whether circular movement or
rectilinear movement is best for the prime mover ; but thus
far opinion seems to be in favour cf the latter;. and the
next question is as to the instrument. The paddle, the
screw, and the pump are up to this time the efficient means.
Steam-moved oars have been tried, but with inefficient re-
sults. The paddle is out of the question for war ships, even
supposing it more efficient for speed than the screw. The
best made paddles should enter the water at one corner, but
so as to make no blow, and in that case they would a; -
proximate to the action of the screw ;" but the side of the
vessel would be a very awkward position for the screw. It
is proved that the best screws are those that enter the water
gradually, with rounded corners, —Once e Week,