RECENT WORK IN AGRICULTURAL SCIENCE. 



CHEMISTRY. 



The determination of nitrogen in mixtures of nitrates, espe- 

 cially in guano, V. Schenke {Chem. Ztg., 20 {1890), No. 101, pp. 1031- 

 1033), — The combination of the Ulscli and Kjeldahl methods proposed 

 by the author in 1893 ' is defended against the criticisms of Haselhoif. 

 He reports comparative tests of this method, the JodlbauerForster 

 metliod, and the Haselhoif method^ on 6 samj^les of guano, nitrate of 

 soda, and mixtures of guano and 2 to 5 per cent of nitrogen in the form 

 of nitrate. The Kjeldahl and Ulsch- Kjeldahl methods gave the calcu- 

 lated percentages of nitrogen. The Haselhoif method gave good 

 results, except when large amounts of uric acid and similar compounds 

 were present. In case of the mixtures the Jodlbauer-Forster method 

 gave good results only when the nitric nitrogen did not exceed 2 per 

 cent. On pure nitrate it gave low results. This is ascribed to loss of 

 nitrogen in evaporating the solution to dryness in this method. It is 

 claimed that no such loss occurs in the author's method. In presence 

 of nitrogen oxids and nitrous compounds both the Ulsch-Kjeldahl and 

 Jodlbauer methods are unreliable. 



Studies of the different methods for determining cellulose, H. 

 SURINGAR and B. ToLLENS {Jour. Landic, 41 (1896), No. 4, pp. 343- 

 356, and Ztsclir. angew. Chem., 1896, No. 24, pp. 742-750).— T\iq authors 

 made an extended study of the principal methods which have been 

 proposed for the determination of cellulose, using filter paper, cotton, 

 sawdust, wood cellulose, jute, etc. These methods included the com- 

 mon Weende method, Franz Schulze method (digestion at low temper- 

 ature with nitric acid and potassium chlorate), Honig method (digestion 

 at 210^ with glycerin and subsequent treatment with hydrochloric 

 acid)^, Gabriel method (digestion at 180° with a glycerin solution of 

 potash )^ Lange method (evaporation to dryness at 180° with concen- 

 trated potash solution)-", and the chloriu method of Cross and Bevan" 



•Chem. Ztg., 17 (1893), p. 977 (E. S. R., 5, p. 222). 

 ^Landw. Vers. Stat., 13 (1894), p. 289 (E. S. R.. (>, p. 609; 8, p. 23). 

 •Chem. Ztg., 14 (1890). pp. 868, 902. 

 -■Ztschr. physiol. Chem., 16, p. 370 (E. S. K., .3, p. 910). 

 5Ztschr. physiol. Chem., 14, \\. 283. 



6 Cellulose, an outline of the cheinlstrv of the structural olomonts of plants, p. 95. 



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