Soap intended to be liquored with silicate of soda should be distinctly strong in free alkali; the crystalline nature of the soap is increased thereby, and the mottled effect intensified. Some makers, however, fit the soap coarsely and allow a nigre to deposit; then, after removing the nigre, or transferring the settled soap to another copper, containing scraps of mottled soap, get the soap into a condition for mottling, and add the silicate of soda solution. To every 1 cwt. of soap, 28 lb. of silicate of soda solution, 32-1/2 deg. Tw. (20 deg. B.) is added, whilst boiling; the strength of the silicate solution, however, will depend upon the proportion of cocoa-nut oil and palm-kernel oil present in the charge. Many soap-makers use 20 deg. Tw. (13 deg. B.) (cold) silicate solution, whilst others prefer 140 deg. Tw. (59.5 deg. B.), with the gradual addition of water to the soap, kept boiling, until the product is in the correct mottling condition, and others, again, use bleach liquor, soda crystals, pearl ash, and salt, together with silicate solution. Considerable skill and experience is necessary to discern when the soap acquires the correct mottling state. It should drop off the spatula in large thick flakes, take considerable time to set, and the surface should not be glossy. When this mottling condition 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.