Turpentine, creosote, acetic acid, charcoal,
coal-tar oils, etc., are also obtained from the same materials as the
wood oil.
* * * * *
SOAP.
By HENRY LEFFMANN, M.D.
Although the use of soap dates from a rather remote period, the
chemist is still living, at an advanced age, to whom we are indebted
for a knowledge of its composition and mode of formation. Considerably
more than a generation has elapsed since Chevreul announced these
facts, but a full appreciation of the principles involved is scarcely
realized outside of the circle of professional chemists. Learned
medical and physiological writers often speak of glycerin as the
"sweet principle of fats," or term fats compounds of fatty acids and
glycerin. Indeed, there is little doubt that the great popularity of
glycerin as an emollient arose from the view that it represented the
essential base of the fats. With regard to soap, also, much erroneous
and indistinct impression prevails. Its detergent action is sometimes
supposed to be due to the free alkali, whereas a well-made soap is
practically neutral.
A desire to secure either an increased detergent, cleansing, or other
local effect has led in recent years to the introduction into soaps of
a large number of substances, some of which have been chosen without
much regard to their chemical relations to the soap itself.
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