I20 PHOSPHATIC MANURES [chap. 



whether this solution might not be substituted for the 

 bones." 



In 1 841, a Mr Fleming of Barrochan had made an 

 experiment with about three-quarters of a pound of 

 dissolved bones, and in 1842 the Highland and Agri- 

 cultural Society offered a prize for an experiment with 

 bones dissolved in sulphuric acid. In January 1842, 

 Professor Johnston, in his published lectures, suggested 

 the use for purposes of manure of acid or soluble 

 phosphate of lime, made by adding sulphuric acid to 

 burnt bones or bone ash: — '^ Acid or biphosphate of 

 lime. — When burned bones are reduced to powder, and 

 digested in sulphuric acid (oil of vitriol) diluted with 

 once or twice its weight of water, the acid combines 

 with a portion of the lime, and forms sulphate of lime 

 (gypsum), while the remainder of the lime and the 

 whole of the phosphoric acid are dissolved. The 

 solution, therefore, contains an acid phosphate of lime, 

 or one in which the phosphoric acid exists in much 

 larger quantity than in the earth of bones. "If the 

 mixture of gypsum and acid phosphate above described 

 be largely diluted with water, it will form a most 

 valuable liquid manure, especially for grass land and for 

 crops of rising corn. In this liquid state, the phosphoric 

 acid will diffuse itself easily and perfectly throughout 

 the soil, and there will speedily lose its acid character 

 by combining with one or other of the basic substances, 

 almost always present in every variety of land." Mr 

 Hannam in Yorkshire, in 1843, claimed to have been 

 the first to carry out this experiment with burnt bones 

 and acid. 



All these experiments, however, had in reality been 

 anticipated by Mr J. B. Lawes, to whom, in May 1842, 

 was granted a patent for making superphosphate, from 

 the specification of which the following extract has 



