CYANAMID — manufacture:, CHEMISTRY AND USES 4I 



In Fig. 3 is plotted the percentage of the cyanamide removed 

 with increase of concentration. This percentage is a maximum 

 at the lower concentrations, but decreases as the concentration 

 increases, until finally a steady value of about 20 per cent, is 

 reached, when the amount of cyanamide disappearing in a 

 given time is constant. The fact that this curve is approxi- 

 mately logarithmic indicates that the primary action is one of 

 absorption, since it is well-known that the more dilute the solu- 

 tion the greater is the percentage of substance taken up by the 

 absorbing surfaces, and that as the concentration of solution 



too 9 



EFFECT OF CONCENTRATION 

 ON REMOVAL OF CYANAMIDE 

 FROM SOIL SOLUTION. 



increases a condition of equilibrium is reached and the ratio 

 of the concentrations in the absorbing surfaces and in the 

 solution becomes constant. 



Fig. 4 shows the absolute quantity of cyanamide removed as 

 the concentration increases. It is practically directly propor- 

 tionally to the concentration. This curve shows the same 

 fact as the curve in Fig. 4, namely, that the ratio of the con- 

 centrations in the absorbing surfaces and in the solution is 



