498 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTTJRE. 



In addition to the study of the cyanamide process itself, the labora- 

 tory has also studied various products which may be made from 

 cyanamide, such as dicyanodiamide, melamine, guanylurea, guani- 

 dine, and related compounds. During the past year our studies on 

 cyanamide derivatives have been largely directed toward a summar- 

 ization of the relationships existing between the various compounds 

 in the series and analytical methods for their accurate determina- 

 tion. The results obtained should simplify to a considerable extent 

 the problems of research in this field. Methods have been developed 

 for preparing the ethyl ester of guanidine carboxylic acid, guanidine 

 carbonate, and urethane. Some of the large number of cyanamide 

 derivatives have already found distinct uses in the manufacture of 

 military explosives, in medicine, and in the arts. 



This class of compounds forms the natural starting point for a 

 whole new field in chemistry, much as certain coal-tar compounds lay 

 at the base of the present dyestuff industry. The sources of these com- 

 pounds heretofore available have made them too expensive to be con- 

 sidered for wide uses, and the industrial aspect of this field in chem- 

 istry has therefore been slow of development. Now that the neces- 

 sary raw materials can be obtained cheaply and in large quantities 

 through cyanamide, this group of compounds presents a very attrac- 

 tive opportunity for industrial chemical research and development. 



While it is not at all likely that the amount of nitrogen going into 

 such products would ever approach the tonnage absorbed by the 

 fertilizer industry, the aggregate value of the products might not be 

 so disproportionate. So tliat while the fertilizer industry may draw 

 its nitrogen supply in increasing!}^ greater proportion from sources 

 other than cyanamide, the latter may still have an important mission 

 to perform in supplying the basis for these more specialized com- 

 pounds. 



The laboratory has made quite definite contributions to the chem- 

 istry of these cyanamide derivatives ; but having thus opened the way 

 and connected the subject with its other more basic work on the 

 actual fixation of nitrogen, it is felt that further developments in this 

 line may now very properly be left for the greater part at least to 

 the research laboratories of the universities and the industries. 



In experiments on the actual use of fertilizers, the laboratory has 

 cooperated with the Bureau of Plant Industry. During the year a 

 bulletin under joint authorship has been prepared and is now in press 

 (United States Department of Agriculture Bulletin 1180) covering 

 the results of field work for several years past on the comparison of 

 the effects of cyanamide and various other forms of fixed nitrogen on 

 different crops under a variety of conditions. One of the most prom- 

 ising developments of the work is the use of mixtures of cyanamide 

 with neutral or basic phosphates. It had come to be generally as- 

 sumed that about 60 pounds of cyanamide per ton of mixed fertilizer 

 was an upper limit of good standard practice. This was based, how- 

 ever, almost entirely on experience with mixtures containing acid 

 phosphate, which at present is used almost exclusively in this coun- 

 try. Experiments detailed in the forthcoming bulletin and which 

 are being further checked and extended in the field seem to indicate 

 that in the case of certain crops at least, notably corn, when acid 

 phosphate is replaced by neutral or basic phosphates, such as calcined 



