102 OF FERTILIZERS. 



340. Plaster, or plaster of Paris, as it is often called, 

 is sulphate of lime : and the valuable effects it produces 

 upon soils are owing to its supplying them not only with 

 lime, but with the very important and often essential 

 element of sulphur. 



341. Sulphur, or brimstone, is present in nearly all 

 parts of vegetables and of animals. Mustard seeds and 

 the seeds of all other cruciferous plants contain a large 

 proportion of sulphur. It also exists in the white of 

 eggs, in the curd of milk, in hair and in wool. 



Several very valuable salts are formed by sulphuric acid 

 or oil of vitriol. By combining with potash, it forms sul 

 phate of potash ; with soda, sulphate of soda, Glauber s 

 salt ; with lime, sulphate of lime, plaster or gypsum ; 

 with magnesia, sulphate of magnesia, Epsom salts ; with 

 alumina, sulphate of alumina ; with oxide of iron, sul 

 phate of iron, copperas. And it is from these and other 

 similar compounds that plants derive the sulphur found 

 in them. 



342. Plaster produces a striking effect upon the water 

 in which it is dissolved, &quot; such water, being incapable of 

 cooking vegetables and of dissolving soap, is called hard 

 water; but it may be very easily and economically con 

 verted into soft ivatcr, and rendered fit for domestic and 

 culinary purposes, by adding to it a small quantity of 

 ordinary carbonate of soda, in the proportion of about 

 half an ounce per gallon.&quot; Normandy. 



Carbonate of lime is formed, which settles to the bot 

 tom as a white sediment, from which soft water may be 

 poured off. 



343. Plaster has also the property of being decomposed 

 by the carbonate of ammonia. It is thus turned into 

 sulphate of ammonia, which is not volatile at a common 



