lOO CYANAMID — MANUFACTURE, CHEMISTRY AND USES 



ing each sample three times with 250 cc. water each time. The 

 following results were obtained : 



Sample number 284 285 294 295 308 



Per cent. Per cent. Per cent. Per cent. Per cent. 



Total nitrogen 15.76 13.57 13-29 14.00 16.40 



Soluble nitrogen, 1st 250 cc. 14.71 12.13 11.89 12.78 14.50 

 *' " 2nd ** . 0.08 0.32 0.32 0.32 0.49 

 " " 3rd '* . 0.12 0.12 0.12 0.08 0.33 

 Total soluble nitrogen ... . 14.91 12.57 12.32 13.18 15.32 

 Active insoluble nitrogen. 0.14 0,22 0.23 0.22 0.31 

 Inactive " '« ... 0.71 0.78 0.73 0.60 0.77 

 Total nitrogen as water sol- 

 uble and active insoluble 95.5 94.3 94.5 95.7 95.3 



It is seen that with this change in the procedure the water- 

 soluble nitrogen averages 93.5 per cent, and the total available 

 95.1 per cent. 



The percentage of available nitrogen revealed by the 

 modified alkaline permanganate method is practically a ques- 

 tion of the solubility and the rate of solution of Cyanamid 

 nitrogen in the initial washing with distilled water. The in- 

 fluence of size of sample and of rate of solution is shown in 

 the preliminary experiments on page 96. It is evident that to 

 determine the true amount of water-soluble nitrogen in 

 Cyanamid by the modified alkaline permanganate method a 

 longer period of contact should be allowed between sample 

 and solvent in the initial washing, or more solvent should be 

 used. The simplest way would be to let the sample stand in a 

 flask with distilled water for 24 hours and filter, or to agitate 

 on a shaking machine for about three hours. 



Whether or not the availability determined by the perman- 

 ganate methods corresponds with the fertilizer efficiency of 

 Cyanamid is a question principally of determining what the 

 fertilizing efficiency is, since the permanganate methods are 

 easily carried out in the laboratory. The concensus of opinion 

 seems to be that Cyanamid has about the fertilizing value of 

 sulphate of ammonia, and this is about 95 per cent, of the 

 efficiency of nitrate of soda, as an average of all kinds of 

 conditions, favorable and unfavorable, that might occur in 



