CYAN AM ID — manufacture:^ CHEMISTRY AND USES 35 



It will be noticed that on the third day the amount of 

 cyanamide that had been decomposed was about the same 

 whether glucose were present or not, in fact there seems to 

 be slightly more decomposition when the glucose was omitted, 

 though this is probably accidental. At the end of 9 days, 

 however, the glucose treated sample was entirely decomposed, 

 while the untreated sample still contained about one-third of 

 the original cyanamide. Cladosporium in the presence of soil 

 caused a rapid decomposition, complete in 3 days. It is at 

 once evident that the sand soil used did not contain appre- 

 ciable amounts of cladosporium, or the decomposition would 

 have been more rapid in the first two cases. During the first 

 three days the samples with and without glucose behaved very 

 much alike, hence the same processes were taking place, and 

 these were probably chemical; then, however, the glucose 

 treated sample became suddenly very active, and this prob- 

 ably represents the beginning of bacterial participation. 



It should be noted in the above experiment that the concen- 

 tration of cyanamide applied was 0.022 per cent., as compared 

 with the 0.5 per cent, used by Ulpiani. It is likely that the 

 latter concentration is too great to permit bacterial activity, 

 except under the most favorable circumstances and then only 

 with certain bacteria. The quantity of cyanamide applied by 

 Kappen is equivalent to about 600 pounds of nitrogen per 

 acre half-foot of soil. In agriculture, 60 pounds per acre is 

 a maximum that is seldom exceeded. 



Kappen succeeded in isolating pure cultures of five fungi 

 capable of decomposing cyanamide; two of them, penicillum 

 brevicaule, and the cladosporium mentioned above, grew even 

 in 2 per cent, solutions, but the others required lower concen- 

 trations. It is therefore difficult to estimate the importance 

 of these special fungi to this problem. It is certain that they 

 do not occur commonly in all soils (those used by Ulpiani 

 for instance and the ordinary soils of Kappen) to any great 

 extent, and it is doubtful if they ordinarily have much to do 

 with Cyanamid decomposition in the soil. 



