1918.] AGRICULrURAL CHEMISTRY AGROTECHNV. 711 



continue the action. With the thickness secured by four layers of the gauze, 

 and the correct flow by gas, the heat developed is sufficient to maintain the cata- 

 lyst at the correct temperature after the action has started. Less than four 

 layers allows a slip of ammonia through the catalyst. 



The preparation of cyanamid, A. E. Ostekberg and E. C. Kendall (Jour. 

 Biol. Chem., S2 (1917), No. S, pp. 297, 298).— A method by which cyanamid may 

 be easily obtained in a high State of purity is described as follows : 



Two hundred gm. of calcium cyanamid are mixed in a 3-liter flask with 1,500 

 cc. of distilled water. Into this mixture carbon dioxid is passed until the reac- 

 tion is neutral or only slightly alkaline. The temperature should be kept below 

 40° C. to prevent polymerization. The precipitate is then filtered on a Buchner 

 funnel and washed with water. The filtrate Ls placed in a 3-liter flask, a small 

 amount of talcum added, and the solution concentrated by distillation on a 

 water bath in vacuo until a solid crystalline mass is formed on cooling under 

 cold water. This is extracted three times with ether, the ether distilled off 

 on a water bath, and the remaining solution concentrated over sulphuric acid 

 in vacuo. The method gives a yield of 92 per cent of the theoretical. 



Dried blood in agricuJture; its importance and researches on its adultera- 

 tion, M. SiKOT and G. Joret (Ann. Sci. Agron., Jf. ser., 5 {1916), No. 10-12, pp. 

 47S-495). — The authors emphasize the importance of detecting adulteration in 

 dried blood, describe the usual methods of preparing blood and roasted leather 

 for fertilizers, and discuss the detection of adulteration in dried blood by the 

 microscopic method, its general characteristics, tannin content, and proximate 

 analysis. 



The most common adulterant of dried blood is roasted leather meal, which, 

 from the point of view of rapidity of as.similation of nitrogen, is of very little 

 value compared vpith dried blood. Detection of this adulterant Is difficult by 

 microscopic examination on account of the presence in a poorly prepared blood 

 of particles closely resembling those in leather meal. Pure samples of dried 

 blood and of leather meal can be differentiated by their general appearance, 

 odor, and behavior on heating, but in a mixture of the two the tannin test is 

 tlie best indication of the presence of the leather meal. 



Tables are given of the content of nitrogen, moisture, ash, total organic mat- 

 ter, and protein in pure dried blood, leather meal, dried meat, dried horn, and 

 other fertilizers. The difference between the total organic matter and protein 

 is a useful factor in detecting adulteration of dried blood, for the pure blood 

 gives a value of from to 3..5, while in adulterated bloods the values are con- 

 siderably above 3.5. Composite fertilizers sold under the name of organic fer- 

 tilizers and characterized by mixtures of mineral superphosphates and organic 

 nitrogen in the form of blood, leather, or dried meat have been e!s:amined and 

 the amount of leather determined by this factor. 



In 112 samples of dried-blood fertilizers examined by the authors from Sep- 

 tember, 1913, to March, 1917, 46 were adulterated, those by leather alone exceed- 

 ing 26 per cent. Attention is called to the importance of determining in a fer- 

 tilizer not only the amount of nitrogen but its nature. 



Tlie ratio of total nitrogen to soluble nitrogen in flour, E. Rousseaux and 

 M. SiEOT {Ann. Falsif.,' 10 {1917), No. 109-110, pp. 556-560 ) .—Continuing in- 

 vestigations previously noted (E. S. R., 31, p. 809), the authors have deter- 

 mined the ratio of total to soluble nitrogen in several varieties of flour with 

 particular reference to the baking quality of the flour. The following results 

 were obtained : Flour with extraction value below 70 per cent, 5.73 ; extraction 

 value above 70 per cent, 6.2 to 7.3 ; American flour rich in gluten, 7.8 to 8 ; .sus- 

 pected flour, L6 to 5 ; corn flour, 5.5 ; rye, 4.4 ; a mixture of 15 per cent rye and 



