RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY. 



Heat of evaporation of water, A. W. Smith (Phus. Rev., 25 {1901), No. 3, 

 pp. lJf5-nO, figs. 3). — From experiments reitorted iu full the author deduced 

 the following formula for the heat of evaporation of water at temperatures be- 

 tween 14 and 40° C. : L(in joules) =2502.5— 2.43T. "The probable error of 

 values computed from this formula is 0.5 joule. These results are expressed 

 in international joules; that is. in terms of the international ohm and 1.43400 

 volts for the E.M.F. of the Clark cell at 15° C." For comparison the results 

 are also expressed in mean calories, assuming that a mean calorie is equivalent 

 to 4.1S87 international joules, which would make the formula L(in mean 

 calories) =597.44 — 0.5S0T. 



The data reported show that the same amount of heat is required to evap- 

 orate a gram of water whether the external pressure be great or small. A 

 table is given showing the heat of evaporation of water from 10 to 45° C. 



In calorimetric experiments with man and animals the heat evaporation of 

 water at 20° C. is one of the factors used. This is given by fhe author as 

 2,453.0 international joules or 585.84 mean calories. 



The quantitative synthesis of arg-entic nitrate, and the atomic weights of 

 nitrogen and silver, T. W. Richards and (i. S. Forbes {Carnegie Inst. Washing- 

 ton Pub. 69, pp. 47-65, figs. 2; Chem. News, 96 (1907), Nos. 2-i98, pp. 180-183, 

 fig. 1; 2^99, pp. 190-193, fig. 1). — The outcome of these investigations was 

 " that 100 parts of pure silver produced 157.47!) parts of argentic nitrate. If, 

 then, silver is taken as 107.93, nitrogen must be 14.037 ; or if silver is taken as 

 107.88, nitrogen must be 14.008, oxygen being 16." 



A revision of the atomic weight of potassium, T. W. Richards, A. Staeh- 

 LER, and E.Mueller {Carnegie Inst. Waslringtun Pub. 69, pp. 7--'f-'/ ; Chem. News, 

 96 {1907), Nos. 2Ji9J,, pp. 133-136; 2.'i95, pp. 1J,5-1J,8 ; 2.'i96, pp. 156-159; 2.',97, pp. 

 170-172). — The authors conclude from the review of all available data tbat 

 " there seems to be little reason to doubt that the outcome of the present investi- 

 gation, 39.114, really represents the atomic weight of potassium." See also a 

 previous account (E. S. R., 18, p. 1107). 



Method for rapid measurement of carbon and hydrogen in organic sub- 

 stances, P. Breteau and H. Leroux {.Jour. Pharm. et Cliim., 6. scr., 26 {1907), 

 No. 9, pp. 385-392, figs. 2). — The authors describe an apparatus and method of 

 procedure in which they have sought to combine various advantages that have 

 been gained through the modification, by different investigators, of the classical 

 method of Liebig for the measurement of carbon and hydrogen in organic 

 substances. 



Hydrolysis of excelsin, T. B. Osborne and S. H. Clapp {Amer. Jour. 

 Physiol., 19 {1907), No. 1, pp. 53-60, pi. /).— The globulin excelsin from the 

 Brazil nut, according to the authors, on hydrolysis showed no striking feature 

 except the unusually large proportion of arginln (16.02 per cent) which was 



610 



