Page:Treatise on Soap Making.djvu/52

36 quantity of common salt is necessary; nor is the soap ever so firm and hard as when they are combined with kelp, &c.; and soap made with these ashes alone, is always apt to get softer by age. Upon this account, pearl ashes seem much better calculated for soft, or green soap, than hard. A boil, however, with these pearl ashes, after the rosin have been melted, is peculiarly serviceable for killing the tallow, (according to the common phrase); it converts the whole mass in the pan to a consistence, or thin weak soap. But this will be better understood when we come to the operation of boiling or making the soap; a process which we shall immediately set about.

Let us now suppose that every thing is ready for commencing the operation upon a moderate scale, viz. that there is a small soap-pan, capable of casting from 20 to 24 cwt. of soap, six or eight iron vats, or caves,