SOAP-MAKING. 209 



frames or moulds, to cool and harden. Good soap 

 contains generally about one-third of its weight of 

 water ; the exact proportion depends upon the mode 

 in which it is made. It is possible to prepare a solid 

 soap containing as much as two-thirds of its weight 

 of water. 



526. Such soap looks very well whilst fresh, but it 

 soon begins to shrink and shrivel up when kept. The 

 retailers of soap generally store up their soap in a 

 damp place, where it shall lose as little weight as 

 possible by evaporation ; sometimes they keep it in 

 strong brine, and many devices are adopted to in- 

 crease the weight of soap, by causing it to take up a 

 larger proportion of water. 



527. Common yellow soap is made in the same 

 way as white or curd soap ; but it contains, in addition, 

 a quantity of resin. This is a useful addition ; and 

 such soap is both good and cheap. The yellow soap 

 is softer and more soluble than hard white soap ; there 

 is consequently more of it wasted in washing. 



528. Black, or soft soap, is made entirely with 

 potash, and is generally manufactured from the com- 

 monest and cheapest oils ; it is semi-transparent, and 

 has usually a dark greenish color, speckled through- 

 out with little white spots. These spots are caused 

 by the addition of tallow, which, though it does not 

 really in any way add to the goodness of the soap, is 

 generally mixed up with it, because many persons 

 imagine that the soap is not good, unless it exhibits 

 this peculiar appearance. 



IS* 



