6 MANUFACTURE OF AMMONIA 



the alkaline liquor obtained by the destructive distillation of 

 horn or bone. The products of the distillation consisted in 

 part of an aqueous liquid containing much carbonate of 

 ammonia, and in part of a fcetid oil floating above it. After 

 removing the oil the ammonia was separated either by crystal- 

 lisation as sulphate, or by sublimation as chloride. Until the 

 introduction of coal gas for lighting purposes the distillation 

 of horn, bone, feathers, wool, blood, soot, and other nitrogenous 

 organic substances was the process almost universally resorted 

 to for the manufacture of ammonia. At the present day 

 ammonia salts are still obtained as bye-products of the dis- 

 tillation of such materials, but the quantity thus manufactured 

 is relatively very small. 



The use of coal gas for illuminating purposes commenced 

 with the beginning of the present centutry ; the first building 

 Boulton & Watt's Foundry in Soho being lit with coal gas 

 in 1798, and the first street Westminster Bridge in 1813. 

 The ammoniacal liquid and tar produced by the distillation 

 of coal were for many years literally waste products. The 

 ammoniacal liquid appears to have been occasionally diluted 

 and applied to land as a manure, but with unsatisfactory results. 

 The position of affairs in 1842 may be gathered from two 

 paragraphs in the excellent Prize Essay by Dr. George 

 Fownes, published in the Journal of the Royal Agricultural 

 Society, IV., 498. On page 541, he says : 



" The only purely azotized manure is the ammoniacal 

 liquid of the gas works .... This liquid has been tried by 

 many persons as a manure for corn, but with very variable 



success, as may be expected from its indefinite nature 



The best mode of using this substance will certainly be to 

 reduce it to an impure ammoniacal salt, sulphate or chloride, 

 so as to get rid of the sulphuret, sulphite, etc., which can 

 hardly fail to be prejudicial to vegetable life, and then to apply 

 such salt scattered over the ground in a sparing manner; 

 always on the supposition that the compounds mentioned 

 have been shown to be capable of assimilation by the plant." 



At the close of his essay, his knowledge of the enormous 

 quantity of nitrogen stored in coal leads him to a prophetic 



