RECENT WORK IN AGRICULTURAL SCIENCE. 



AGKICULTURAL CHEMISTRY. 



Thermo-chemistry, J. Tiiomsen, trans, by Katharine A. Burke {London 

 (iiul New York, 1908, pp. XV-{-49o, figs. 8). — In the Introduction the author con- 

 ^liders the object of thermochemical research, formulas, symbols, and prin- 

 ciples, and outlines experimental methods. The volume is then divided into 

 four parts, the formation and properties of aqueous solutions, compounds of 

 nonmetals. compouuils of metals with nonuietals, and organic substances. 

 Special interest attaches to the last section, in which the heat of combustion of 

 volatile organic substances is one of the principal subjects considered. As a 

 whole, the volume summarizes the author's investigations and results on thermo- 

 chemistry. The research was undertaken, as is pointed out in the preface of 

 the volume, to study in as systematic and complete a manner as possible " the 

 investigation of the heat phenomena of the more important chemical. i*eactions, 

 and by the interpretation of these results to gain some further knowledge as 

 to the real nature of chemical processes." 



New gravimetric methods, P. Jannasch {Verhandl. Natiirhist. Med. Ver. 

 Heidelberg, n. ser., 9 (1908), No. 1, pp. 7Ji-86, figs. 2).— Methods are described 

 for the indirect determination of carbon dioxid and nitric acid in nitrates by 

 means of sodium tungstate fusion ; the gravimetric determination of carbon 

 dioxid by expulsion with concentrated sulphuric acid and collection of the gas 

 in soda-lime absorbers ; and the quantitative volatilization of arsenic from solu- 

 tions by means of hydrochloric acid and hydrazin sulphate. 



A simple method for the determ.ination of nitrate and nitrite nitrog'en in 

 mixtures and in the presence of organic substances, T. Zeller {Landiv. Vers. 

 8tat.. 70 {1909). No. 1-2, pp. lJ,.J-L5.'i; <ihs. in Chem. Ztg., 33 {1909), No. 26, 

 Repert., p. 121 ; Analyst, 3J, {1909), No. 398, pp. 2-'il, 242).— The author states 

 that when a solution containing nitrite is boiled with ammonium chlorid solu- 

 tion of known strength and afterwards distilled with caustic magnesia the 

 amount of ammonia thus obtained corresponds to the nitrite nitrogen in the 

 original solution. 



The method proposed for examination of solutions containing mixtures of 

 nitrate, nitrite, and organic matter is as follows : Boil the solution to be tested 

 with a measured amount of ammonium chlorid solution of known strength in 

 a 100 cc. flask until it is reduced to a small volume, about 2 cc, fill to the mark 

 with water and distill 40 cc. of the solution with caustic magnesia. Digest 

 another 40 cc. of the solution with sulphuric acid and iron and distill with 

 caustic soda. The difference between the amount of nitrogen so obtained and 

 that found in the first determination corresponds to the nitrate nitrogen. Any 

 ammonia which may have been in the solution originally should be determined 

 in ;i sei)arate portion of the solution by distillation with magnesia. 



A nitrometer provided with means for correcting the barometric pres- 

 sure, Herman {Bull. Soc. Chim. Belg., 22 {1908), No. 12, pp. Jt'iO--'il'h f'd- 1 ; 



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