de of iron is
diffused through the soap of its well-known black color, giving the
familiar marbled appearance to it. When the soap is cut up into bars,
and exposed to the air, the protoxide passes by absorption of oxygen
into peroxide; hence, a section of a bar of Castile soap shows the outer
edge red-marbled, while the interior is black-marbled. Some Castile soap
is not artificially colored, but a similar appearance is produced by the
use of a barilla or soda containing sulphuret of the alkaline base, and
at other times from the presence of an iron salt.

MARINE SOAP is a cocoanut-oil soap, of soda containing a great
excess of alkali, and much water combination.

YELLOW SOAP is a soda soap, of tallow, resin, of lard, &c. &c.

PALM SOAP is a soda soap of palm oil, retaining the peculiar
odor and color of the oil unchanged. The odoriferous principle of palm
oil resembling that from orris-root, can be dissolved out of it by
tincturation with alcohol; like ottos generally, it remains intact in
the presence of an alkali, hence, soap made of palm oil retains the odor
of the oil.

The public require a soap that will not shrink and change shape after
they purchase it. It must make a profuse lather during the act of
washing. It must not leave the skin rough after using it. It must be
either quite inodorous or have a pleasant aroma. None of the above soaps
possess all these qualities in union, and, therefore, to produce such an
article is the object of the perfumer in his remelting process.

Prior to the removal of the excise duty upon soap, in 1853, it was a
commercial impossibility for a perfumer to _manufacture_ soap, because
the law did not allow less than one ton of soap to be made at a time.
This law, which, with certain modifications had been in force since the
reign of Charles I, confined the actual manufacture of that article to
the hands of a few capitalists. Such law, however, was but of little
importance to the perfumer, as a soap-boiling plant and apparatus is not
very compatible with a laboratory of flowers; yet, in some exceptional
instances, these excise regulations interfered with him; such, for
instance, as that in making soft soap of lard and potash, known, when
perfumed, as _Creme d'Amande_; or unscented, as a Saponaceous Cream,
which has, in consequence of that law, been entirely thrown into the
hands of our continental neighbors.

FIG SOFT SOAP is a combination of oils, principally olive oil
of the c