CYANAMID — MANUFACTURE, CHEMISTRY AND USES 57 



experiment, soil was sterilized by being held several days in 

 an atmosphere of chloroform vapor, and was compared with 

 untreated soil as in the previous experiments, with the follow- 

 ing results: 



With chloroform Without chloroform 

 mg. mg. 



Cyanamide nitrogen applied 33.00 33.00 



Cyanamide nitrogen after 2 days ... 23.00 0.00 



The addition of chloroform to the soil therefore greatly hin- 

 ders the decomposition of the cyanamide, but does not prevent 

 it. It is quite probable that in all of the experiments made by 

 Kappen, except those where high temperatures were employed, 

 bacteria participated in the decomposition of the cyanamide 

 by converting the urea into ammonium salts, thus hastening 

 the hydrolysis of the cyanamide. 



CONCLUSIONS. 



From the above experiments on the conversion of cyanamide 

 the following conclusions can be drawn: 



I. Calcium cyanamide in contact with moist soil undergoes 

 a decomposition to the form of ammonium salts in three inde- 

 pendent stages. The first stage is a complete hydrolytic sepa- 

 ration of the calcium from the cyanamide, induced by the 

 selective absorption of calcium by the soil, and its probable 

 precipitation as calcium carbonate. (See p. 37). The second 

 stage is a hydrolysis of cyanamide entirely to urea; the third 

 stage is a transformation of urea to ammonium salts. 



II. The cyanamide disappears from the soil solution by two 

 processes : 



(a) Absorption and concentration of cyanamide molecules 

 in the limiting stratum between the soil solution and the soil 

 particles. This takes place during the first few moments of 

 contact. (See pp. 37 and 38). 



(b) Removal of l^e cyanamide molecules from the limiting 

 stratum by hydrolysis to urea under conditions of high surface 

 pressure and concentration. (See p. 40). 



III. The greatest velocity of hydrolysis occurs when the 



