162 MANURE. 



oil is produced. In soap making, the alkali used, de- 

 composes stearine, and oleine, combining with their 

 acids, which thus are converted into stearates, mar - 

 garates, and oleates of alkali, or soap, while the gly- 

 cerine remains free in the spent ley with the salts, 

 which that contains. 



228. The proportion of glycerine, in fat and oil, 

 is about 8 per cent. Its composition is — 



Carbon, 40-07 f These are in such ] Carbon, 24-71 

 Oxygen, 51-00 O^T^t [«C™ M- 17-85 



Hydrogen 8*92 [carburetted hydrogen J Water, 57 -37 



Glycerine is transparent and liquid, and was called 

 the sweet principle of oils, from its sweet taste. 



229. The glycerine is thus the organic, or geine 

 part of salt ley. Its proportion in that will vary, if 

 the spent ley is boiled, as is usual, upon a fresh por- 

 tion of tallow, which adds its quantity of glycerine, 

 in proportion to the alkali in the ley. 



230. The salts are various, and depend on the 

 kind of alkali used to form the ley. 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 

 ley 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 pot- 



