ORGANIC NITROGEN FERTILIZERS 117 



process are allowed to run away into ponds; where the water 

 flows away and the solids settle out. After some air-drying 

 a fertilizer is obtained which consists of lime compounds, 

 with a fair amount of organic matter containing nitrogen. 

 The composition of this material is very variable, wet 

 samples containing J % of nitrogen and 13 % of lime, but if 

 slightly dried the value may be easily doubled, or even trebled. 

 Various clippings of waste materials, known as fleshings, 

 from the raw skins are sorted into two kinds, the dark 

 coloured being used for joiners' glue and the pale for the 

 manufacture of gelatine. They are well washed and treated 

 with sulphuric acid, again well washed, and then boiled up 

 in boilers for from 6 to 10 hours. A small amount of oil 

 is skimmed off the top, the gelatine remains in solution, 

 and the fibrous matter sinks to the bottom. This fibrous 

 matter which is left at the bottom of the boiler is dried and 

 sold as scutch. Being very fibrous, it must be broken up in 

 a disintegrator, which produces a well-powdered material 

 containing from 5 to 7 % of nitrogen. (Fig. 5.) leather 

 clippings, in the raw state, are of little value as a 

 fertilizer, but by roasting or steaming some improvement 

 can be effected. A better treatment is by means of acid. 

 Ity using sulphuric acid of a specific gravity of about i'6 %, 

 heated to 140 F., raw leather and other organic nitrogen 

 substances can be dissolved. The resulting mass then can 

 be used for the manufacture of compound manures. 



REFERENCES TO SECTION II. 



Voelcker, Journ. Roy. Agric. Soc., 1908, 1909 and 1910. 



" The Nitrogen Problem and the Work of the Nitrogen Products 

 Committee," Jouvn. Soc. Chem. Ind., 1917, p. 1196. 



Cowie, " Decomposition of Cyanamide and Dicyanodiamide in the 

 Soil," Journ. Agric. Science, 1919, p. 113. 



"World's Production of Calcium Cyanamide," 1913-18, Journ. Soc. 

 Chem. Ind., 1919, p. 271 R. 



Turrentine, "Fish Scrap Fertilizer Industry of the Atlantic Coast," 

 Journ. Soc. Chem. Ind., 1914, p. 270. 



Witherspoon, " Manufacture of Calcium Carbide," Journ. Soc. Chem. 

 Ind., 1913, p. 113. 



Allmand and Williams, " Calcium Carbide and Cyanamide," Journ. Soc. 

 Chem. Ind., 1919, p. 304 R. 



Mukerji, " Handbook of Indian Agriculture," p. 218 (Thacker, Spink). 



Maze, Vila et Lemoigne. " Transformation de la cyanamide en uree par 

 les microbes du sol," Comp. Rend., 1919, pp. 804, 921. 



