12 BULLETIN 97, U. S. DEPARTMENT OF AGRICULTURE. . 



Calcium cyanamid, according to L. Vuaflart, 1 may be tested, for as 

 follows: "The presence of calcium cyanamid in a mixture containing 

 other fertilizers can be detected by its odor, alkaline reaction, the 

 large amount of calcium present, the black residue which is left after 

 treating the sample with water, and the yellow precipitate obtained 

 with silver nitrate which is insoluble in ammonium hydroxid but sol- 

 uble in nitric acid. An impurity often present in the latter is a black 

 acetylene silver insoluble in nitric acid. If organic fertilizers are 

 present in the mixture, these can be detected by dissolving the 

 cyanamid in hydrochloric acid, when the organic matter will remain 

 behind as a black residue. Sulphuric acid added to such fertilizers 

 will yield a brown solution." 2 



Basic slag contains a rather large amount of material attracted by 

 an ordinary horseshoe magnet. The nonmagnetic material is trans- 

 parent under the microscope, with a bluish color. It is anisotropic 

 and biaxial. Tetracalcium phosphate is monoclinic and the double 

 refraction is positive; but this can not always be seen in the com- 

 mercial material. The refractive index of the transparent commer- 

 cial material is very near 1.64. The biaxial nature and high index 

 distinguished basic slag from any of the other substances treated of 

 here. 



Shells can be easily distinguished by their obvious shelly structure. 



Cottonseed meal has a predominantly yellow color with brownish 

 hull particles, and usually some cotton lint. Often it can be detected 

 with the naked eye and is easily identified with the microscope. 3 



Raw lone meal is whitish in color. Mounted in oil, under the micro- 

 scope, evident bone structure is seen. 4 



Steamed hone meal is very similar to raw bone meal, and it is not 

 always possible absolutely to distinguish the two. The steamed bone 

 may be somewhat darker in color, has a friable appearance, and does 

 not show the sharp angles and edges seen in the raw product. An 

 empyreumatic odor indicates the nature of the material. 



Peat, humus, much, etc., vary very much. The vegetable matter of 

 the material, however, indicates its nature. 



Dried Hood, megascopic ally is blackish, dull dark red, and dark 

 purplish in color. It is somewhat brittle. Microchemically blood 

 may be tested for in numerous ways, e. g., thchaemin test, guaiacum 

 test, spectroscopic examination of the coloring matter, recognition of 

 blood corpuscles, etc. 5 



i Ann. Falsif., 4 1911 . No. 32, pp. 321-324. Quotation and reference taken from Expt. Sta. Rec, £6, 

 SG4 (1012). 



2 A general discussion of cyanamid will be found in "Cyanamid," by E. J. Pranke, Easton, Pa., 1913. 



» For details of cell structure and technique see Uanausek-Winton-Barber, The Microscopy of Technical 

 Products, 1907. 



4 llanausek, loc. cit. 



* See Allen, Commercial Organic Analysis, Vol. IV, 1898. 



