has been obtained, the colouring matter,
which would be ultramarine for the blue mottled and manganese dioxide
for the grey mottled soap (3-4 lb. ultramarine or 1-3 lb. manganese
dioxide being sufficient for 1 ton of soap), is mixed with a little
water and added to the boiling soap--the boiling is continued until all
is thoroughly amalgamated, and when the steam is shut off the contents
of the pan are ready for cleansing.

Mottled soap is run into wooden frames, which, when full, are covered
over and allowed to cool very gradually. On cooling slowly, large
crystals are produced which result in a distinct bold mottle; if the
cooling is too rapid, a small crystal is obtained and the mottle is not
distributed, resulting in either a small mottle, or no mottle at all,
and merely a general coloration. In fact, the entire art of mottling
soap consists in properly balancing the saline solutions and colouring
matter, so that the latter is properly distributed throughout the soap,
and does not either separate in coloured masses at the bottom of the
frame, or uniformly colour the whole mass.

A sample of the soap should test 45 per cent. fatty acids, and the
amount of salt would range from 1/2 to 1 per cent.

Some of the English mottled soaps, especially those made from materials
which give a yellow-coloured ground, are bleached by soaking in brine,
or pickling in brine containing 2 per cent. of bleach liquor. The
resultant soap has a white ground and is firm. The bleach liquor may be
made by mixing 1 cwt. bleaching powder with 10 cwts. of soda ash
solution (15 deg. Tw., 10 deg. B.), allowing to settle, and using the clear
liquid, or by mixing 2 parts soda ash solution with 1 part of bleaching
powder solution, both solutions being 30 deg. Tw. (18.8 deg. B.).

_Milling-base._--The materials generally used are tallows and cocoa-nut
oils of the finest quality. The tallow is thoroughly saponified first,
and the graining is performed by the aid of caustic soda lye in
preference to salt. The half-spent lyes are withdrawn, and the cocoa-nut
oil added to the pan. This is saponified, and when the saponification is
complete, "boiling-on-strength" is proceeded with. Special care should
be devoted to the "boiling-on-strength" operation--its value in good
soap-making cannot be over-rated--and perfect saponification must be
ensured. The half-spent lyes are allowed to deposit during the night,
and the soap must be carefully examined next morn