-^ MANURE. 19i 



its quantity of glycerine, in proportion to the alkali in the 



230. The salts are various, and depend on the kind of 

 alkali used to form the lye. The . alkali is derived from 

 barilla, from soda or white ash, from potash, or from ashes. 

 Hence, no general statement can be given which shall express 

 the value of spent lye salts. That some idea may be formed 

 of its components, it may be divided into two kinds : 1st, 

 that produced from soft soap, or from ashes, or potash ; 

 2dly, that from hard soap, barilla, or soda-ash. A boil of 

 2000 lbs. of soft soap requires 150 bushels of ashes, and its 

 spent lye contains, in addition to a little free potash, the fol- 

 lowing salts, derived from ashes : 



130 lbs. of sulphate of potash, 

 6 " of muriate of potash, 

 36 " of silicate of potash, 



allowing the ashes to have been a mixture of oak, bass, and 

 birch woods. Besides these, in the process of soap-making, 

 in order to make the soap "grain," common salt is added. 

 A chemical change is thus induced, the potash soap is changed 

 to soda soap, or the soft to hard. The soda of the salt enter- 

 ing the soap is replaced by the potash, which combines with 

 the acid of the salt, that is chlorine, or muriatic acid. In 

 other words, common salt, or chloride of sodium, or muriate 

 of soda is changed to chloride of potassium, or muriate of 

 potash, which is thus added to the spent lye. The proportion 

 of salt added, varies, but it may be stated in general, 7 bush- 

 els, or 500 lbs. to 150 bushels of ashes. In a boil, then, of 

 2000 lbs. of soap, 1200 lbs. of fat, or tallow, containing 

 100 lbs. of glycerine, 150 bushels of ashes, 7 bushels of salt, 

 afford about 200 gallons of spent lye. This contains the 

 glycerine and salts above (230), and affords, per gallon. 



