ids and the effective alkali, the
absent per centage of water is introduced in the calculation, than if
the water is reckoned, which is never completely evolved from soap, even
technically prepared at 302 deg. Fahr., and another determination made of
the fatty acids or alkali _en bloc_ the fatty acids, or even the
alkaline contents.

The method here given partakes of the usual imperfections, that the
fatty acids as well as the unsaponified soap are equally estimated, and
the mixed hydrate or carbonate of the alkali as well as the combined
alkali. The presence of the carbonate can be easily recognized by the
foaming of the soap solution, upon the addition of the sulphuric acid.
These imperfections, however, are of little importance.

It must be granted that the minutely correct determination of the
constitution of soap must be always yielded up to those who are
technically conversant with this department of chemistry, the estimation
of free alkali and unchanged fat excluded in, at least, by certain ages
of the soap. Further, a considerable excess of one or another ingredient
soon betrays itself by a corresponding departure in the soap of the
characteristic properties of a good product, and a small excess can be
judged sufficiently exact from the proportion of the alkali, which,
supposing soda present, should not amount to more than 13 per cent. with
a pure cocoa-nut oil soap, not less than 11.5 per cent. with a tallow
soap; but with palm oil and mixed soaps the one or the other limit
approximates.--_Journal fuer Praktische Chemie._

* * * * *

ON THE NATURAL FATS.

BY DR. CHARLES LOeWIG.

The fats which exist in nature can be divided into the general and the
special; the former exist in almost all plants and parts of plants; the
latter includes only some vegetable substances, as _laurostearine_,
_myristicine_, and _palmatine_. The consistence of fats of the general
kind depend upon the proportions of margarine, stearine, and oleine
contained in them. The former preponderate in the solid fats (butter,
lard, and tallow); and the latter in the fluid ones or oils. According
as an oil contains oleic acid or olinic acid, it is termed a fatty or
drying oil. To the class of fatty oils belong olive, almond, hazel-nut,
beech, rape oils, &c.; to that of drying oils, linseed, nut, hemp,
poppy, grape-seed, oils, &c.; which are used for varnishes.

In the vegetable kingdom the fats are chiefly