SOAP 



223 



color out of clothing ; the cheap soaps are less carefully pre- 

 pared and are apt to have a strong excess of the base ingred- 

 ient ; such soaps are not safe for delicate work. 



205. Soap. If we gather together scrapings of lard, butter, 

 bits of tallow from burned-out candles, scraps of waste fat, or 

 any other sort of grease, and pour a strong solution of lye over 

 the mass, a soft soapy substance is formed. In colonial 

 times, every family made its own supply of soap, utilizing, 

 for that purpose, household scraps often regarded by the 

 housekeeper of to-day as worthless. Grease and fat were 

 boiled with water and hardwood ashes, which are rich in lye, 

 and from the mixture came the soft soap used by our an- 

 cestors. In practice, the wood ashes were boiled in water, 

 which was then strained off, and the resulting filtrate, or lye, 

 was mixed with the fats for soap making. 



Most fats contain a substance of an 

 acid nature, and are decomposed by the 

 action of bases such as caustic soda and 

 caustic potash. The acid component of 

 the grease partially neutralizes the base, 

 and a new substance is formed, namely, 

 soap. 



With the advance of civilization the 

 labor of soap making passed from the 

 home to the factory, very much as bread 

 making has done in our own day. Dif- 

 ferent varieties of soaps appeared, of 

 which the hard soap was the most popu- 

 lar, owing to the ease with which it could 

 be transported. Within the last few 

 years liquid soaps have come into favor, especially in schools, 

 railroad stations, and other public places, where a cake of 

 soap would be handled by many persons. By means of a 



FIG. 157. Liquid soap 

 container. 



