MANURES. 163 



lime of the plaster, or with other alkalies which it 

 may contain in minute quantities. 



The lime contained in the mortar may be useful 

 in the soil for the many purposes accomplished by 

 other lime, and is generally more valuable than that 

 fresh from the kiln. 



GAS HOUSE LIME, ETC. 



The refuse lime of gas works, where it can be 

 cheaply obtained, may be advantageously used as a 

 manure. It consists, chiefly, of various compounds 

 of sulphur and lime. It should be composted with 

 earth or refuse matter, so as to expose it to the action 

 of air. It should never be used fresh from the gas 

 house. In a few months the sulphur will h;fve 

 united with the oxygen of the air, and become sul- 

 phuric acid, which unites with the lime and makes 

 sulphate of lime (plaster,) which form it must as 

 suine, before it is of much value. Having been 



' O 



used to purify gas made from coal, it contains a 

 small quantity of ammonia, which adds to its value. 

 It is considered a profitable manure in England, at 

 the price there paid for it (forty cents a cartload), 

 and, if of good quality, it may be worth more than 

 that, especially for soils deficient in sulphuric acid 

 or lime, or for such crops as are much benefited by 

 plaster. Its price must, of course, be regulated some- 

 what by the price of lime, which constitutes a large 

 proportion of its fertilizing parts. The offensive 

 odor of this compound renders it a good protection 



