RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY. 



New determination of the mechanical equivalent of heat, Y. CRfiMiEU and 

 L. RisPAiL (Compt. Rend. Acad. l^cL [Paris], U7 (1908), No. 18, pp. 793-795, 

 flff. J). — Accordinj? to the authors' determinations, the mechanical equivalent 

 of heat is J = 4.1851 x 10' ergs with an experimental error of .0027 in the deter- 

 mined value which is less than 1/1500. 



On the accumulation of the heat of the sun in various solutions, A. voN 

 Kalecsinszky (Math. u. Natunc. Ber. Ungarn, 21 {1903) [pub. 1907], pp. 

 l-2.'t). — Experiments with fresh water, sea water, and other salt solutions are 

 reported, shownig that the storage of heat is decidedly influenced by the salts 

 in solutiou as well as by the surface covering of the solution, as, for example, 

 with fresh water, olive oil, or petroleum. 



Investigations on the formation and decomposition of ammonia by silent 

 electrical discharges in a Siemens tube, with especial reference to the validity 

 of the law of mass action, J. H. Davies (Ztschr. Phys. Chem., 64 (1908), No. 6, 

 pp. 657-685, figs. 6). — A somewhat detailed study of the effect of varying con- 

 ditions of temperature, pressure, gas mixture, etc., is reported. 



The volumetric composition of ammonia vapor and the atomic weight of 

 nitrogen, P. A. Guye and A. Pintza {Compt. Rend. Acad. 8ci. [Paris], 1^7 

 {ri08). No. 20, pp. 925-928, fig. 1; Mem. Soc. Phys. et. Hist. Nat. Geneve, 35 

 {1908), No. J,, pp. 594-614, pi. 1, figs. 2; abs. in Rev. Sci. [Paris], 5. ser., 10 

 {1908), No. 22, p. 699). — The apparatus and methods employed by the authors 

 in the volumetric analysis of ammonia vapor are described, the causes of error 

 are discussed, and determinations are reported which give an atomic weight 

 for nitrogen between 14 and 14.02, thus confirming the value which is now 

 adopted, namely, 14.01. The volumetric method is considered by the authors 

 too indirect as compared with the gravimetric method. 



The modifications of the Kjeldahl method for the quantitative determina- 

 tion of nitrogen, J. S. Hepbitrn {Jour. Franklin Inst., 166 {1!)08). No. 2. pp. 

 81-99; abs. in Chem. Abs., 2 (1908), No. 23, p. 3206).— A historical review of 

 tests of this method and its modifications, with 39 references to the literature. 

 Determinations of nitrogen in antipyrin using various catalyzers with the 

 sulphuric acid are reported, but in no case was the theoretical percentage 

 obtained. 



A modified Hiifner method for the volumetric determination of nitrogen, 

 V. VON CoRDiER {Ztschr. Analyt. Chem., //7 {1908), No. It, pp. 682-687. fig. 1; 

 abs. in Jour. Chem. Soc. [London], 94 {1908), No. 553, II, p. 983; Chem. Zentbl, 

 1908, II, No. 21, p. 1747. fig. 1). — The method and apparatus (Victor Meyer 

 vapor density apparatus) required are so modified that a larger amount of 

 the material may be conveniently used for the determination, thus insuring 

 more accurate measurement of the gas evolved by the action of the bromin 

 solution. The method as modified is adapted particularly to the analysis of 

 guanidin picrate and similar substances. 

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