AGRICULTURE, WITH CHEMISTRY. 65 



SULPHAT OF ARGIL OR ALLUM. 



ALLUM is a salt dissolvable in fifteen times its weight 

 of water. It is produced in great quantities, by the de- 

 composition of alluminous schyst or slate, on exposure to 

 air, or by calcination. 



Dr. FRANCIS HOME* of Edinburgh, the first person 

 who thought of making experiments with saline bodies 

 in promoting the growth of plants, found no beneficial 

 effects to result from the application of allum to garden 

 mould, the soil on which his experiments were made. 

 Allum is contained in many soils, and is daily forming 

 by the decomposition of alluminous schyst. 



Where found in abundance, the soil is very properly 

 denominated, by country people, a sour soil, on which few 

 vegetables will grow. This sterility is to be correfted 

 l?y lime, by earthy matters containing magnesia, and by 



i alka- 



* Vide Dr. HOME'S most valuable Treatise on that subject, published at Edin- 

 burgh in 1756. 



