37S ANNUAL REPORT OF THE Off. Doc. 



pound. Ill view of the imiuiries that have come to me in the past 

 few months, both from fertilizer manufacturers and others, regard- 

 ing this material, I have judged that a somewhat fuller account of 

 the manufacture and agricuUural uses of the substances of this 

 class might have present interest. » 



Each discovery increasing the range of control by mankind over 

 the purely physical energies has opened the way to a large develop- 

 ment in the number of chemical compounds that can be artificially 

 prepared. This is notably true in the case of the high temperatures 

 attained under conditions well v/ithin human control by the use of 

 the electrical furnace, a simple apparatus in which high tension elec- 

 trical currents are the immediate sources of energy. While dia- 

 monds and rubies have been made in the electrical furnace, one of 

 ihe most valuable products from this new development of human 

 invention has been calcium carbide, the material which is obtained 

 by the fusion of lime and coke, and which decomposes upon reaction 

 with water so as to form caustic lime and the acetylene gas now so 

 widely used for illuminating purposes. 



Further exj)eriment revealed the fact that when calcium carbide 

 is heated with pure nitrogen gas, it gives up some of its carbon and 

 instead takes up nitrogen so as to form calcium cyanamid. 



Calcium cyanamid w^hen in pure condition, is a white compound 

 soluble in w'ater. It contains 35 per cent, of nitrogen and, when 

 brought into contact with superheated steam, gives off the nitro- 

 gen in the form of ammonia. On treatment with mineral acid, cal- 

 cium cyanamid forms the calcium salt of the mineral acid and free 

 cyanamid, a compound that by the simple taking up of water, is 

 converted into urea. Furthermore, cyanamid upon recrystallization 

 from cold water solution yields dicyanamid. Both cyanamid and 

 dicyanamid contain 66 per cent, of nitrogen. They are, however, too 

 expensive for present use as fertilizer materials. 



The crude calcium cyanamid prepared, as above described, from 

 calcium carbide, contains all the impurities of the latter substance 

 together with the carbon separated from it in the manufacturing jiro- 

 cesses. The name given to this crude product is ''''lime intjy^gcnP 

 (in the German, Kalkstickstoff). The quantity of nitrogen in this 

 crude product is usually from 15 to 25 per cent. Since calcium car- 

 bide is always alkaline because of an excess of lime, lime nitrogen 

 likewise possesses this proj)erty. Furthermore, in the production 

 of the carbide, sulfates and phosi>hates that are always present, 

 though in very small quantity, in the limestone, are reduced to the 

 condition of sulfides and phosphides. These compounds liberate, 

 upon contact with moisture, the gases, sulfuretted and phosporetted 

 hydrogen. There is usually present also more or less unchanged cal- 

 cium carbide, but not usually euougli to make possible the setting 

 free of dangerous quantities of acetylene gas, and the insurance com- 

 panies have placed lime nitrogen in the list of products not injured 

 by fire. In order to secure tlie preservation in the fullest measure 

 of the valuable properties of lime nitrogen, and also to prevent the 

 emission of undesirable odors, the manufac+urers coat the exterior 

 portions of the bagged goods with lieavy peTroleum. 



The manufacture of this material is now carried on by two differ- 

 ent processes, one the Frank and Caro process, requiring a high ten- 

 sion current of electricity for the last stage of the process-, the other, 



