56 CYANAMID — manufacture:, CHEMISTRY AND USES 



Cyanamide 



nitrogen in Iron oxide sol. 



milligrams (0.8 per cent. Fco O3) 



Applied 33.04 



After 18 hours 27.77 



' ' 2 days 22.40 



" 4 days 10.08 



The condition of sol is favorable to the conversion, but not as 

 favorable as the condition of gel since the dilution of the 

 cyanamide hinders the reaction. 



In order to determine whether or not calcium cyanamide 

 reacts as readily as cyanamide, a quantity of lime-nitrogen con- 

 taining 33 mg. of cyanamide nitrogen was added to lOO g of a 

 mixture of sand with equal weights of manganese hydroxide, 

 and iron ores No. i and 2, (see page 52). After 24 hours 

 the quantities of cyanamide nitrogen remaining were: 



Milligram 



Manganese 0.00 



Iron ores No. i and No. 2 0.00 



Glass-sand 29. 18 



With cyanamide, glass-sand left 32.34 mg. in solution after i 

 day. The presence of the lime in the lime-nitrogen evidently 

 hastens the decomposition of the cyanamide. 



The effect of pure, calcined iron oxide, FegOg, on 

 cyanamide was determined by mixing glass sand with 5 per 

 cent, of its weight of iron oxide, and treating with cyanamide 

 solution as in the previous experiments. 



Milligram 



Cyanamide applied 33-oo 



" after I day 32.42 



'• 3 days 30.63 



" " 5 days 28.07 



♦♦ *' 8 days 26.56 



Iron oxide therefore has a slow action as compared with the 

 metal hydroxides used. 



EXPERIMENT WITH STERHIZED SOU. 



All of the above experiments of Kappen were made with 

 unsterilized materials; they therefore do not differentiate 

 between physico-chemical and bacterial processes. In this 



