ap from
material containing 50 per cent. rosin.

Fish or marine animal oils--whale, seal, etc., once largely used as raw
material for soft soap, have been superseded by vegetable oils.

The materials must be varied according to the season; during hot
weather, more body with a less tendency to separate is given by the
introduction of oils and fats richer in stearine; these materials also
induce "figging".

The most important material, however, is the caustic potash lye which
should average 40 deg. Tw. (24 deg. B.), _i.e._, if a weak solution is used to
commence saponification, a stronger lye must be afterwards employed to
avoid excess of water in the soap, and these average 40 deg. Tw. (24 deg. B.).
The potash lye must contain carbonates, which help to give transparency
to the resultant soap. If the lye is somewhat deficient in carbonates,
they may be added in the form of a solution of refined pearl ash
(potassium carbonate).

Caustic soda lye is sometimes admixed, to the extent of one-fourth, with
potash lye to keep the soap firmer during hot weather, but it requires
great care, as a slight excess of soda gives soft soap a bad appearance
and a tendency to separate.

The process is commenced by running fatty matter and weak potash lyes
into the pan or copper, and boiling together, whilst the introduction of
oil and potash lye is continued.

The saponification commences when an emulsion forms, and the lye is then
run in more quickly to prevent the mass thickening.

Having added sufficient "strength" for complete saponification, the
boiling is continued until the soap becomes clear.

The condition of the soap is judged by observing the behaviour of a
small sample taken from the pan and dropped on glass or iron. If the
soap is satisfactory it will set firm, have a short texture and slightly
opaque edge, and be quite clear when held towards the light. If the
cooled sample draws out in threads, there is an excess of water present.
If an opaque edge appears and vanishes, the soap requires more lye. If
the sample is turbid and somewhat white, the soap is too alkaline and
needs more oil.

The glycerine liberated during saponification is contained in the soap
and no doubt plays a part in the production of transparency.

_Hydrated soaps_, both smooth and marbled, are included in this
classification, but are _soda_ soaps. Soap made from cocoa-nut oil and
palm-kernel oil will admit of the incorporation of large quantitie