504 EXPEBIMENT STATION RECOED. [Vol.36 



Review: The preparation of conductivity water, J. Kendall {Jour. Amcr. 

 Chem. Soc, S8 (1916), No. 11, pp. 2460-2^66).— The literature on the preparation 

 of conductivity water is reviewed. 



By one distillation in the open air of tap water to which a few cubic 

 centimeters of Nessler's solution had been added a water of specific conductiv- 

 ity 0.9 X 10"' at 25° C. was obtained. By redistillation in silica vessels and 

 collecting the distillate hot, water of specific conductivity 0.2-0.6 X 10'* at 25° 

 was obtained. Such low values, however, were only observed when the dis- 

 tillate was tested at once. On standing, the values rose to 0.8-0.9 X 10'' and 

 remained stationary for some time. The specific conductivity of the water 

 thus obtained is the same as that given by a saturated solution of carbonic acid 

 under atmospheric conditions. 



It is indicated that a water obtained as described, to which a proper cor- 

 rection is applied, is as satisfactory in conductivity work as waters distilled 

 by a more elaborate method. 



A simple mercury sealed ether still, O. C. Smith and D. G. Morgan {Jour. 

 Indus, and Engin. Chem., 8 0916), No. 11, p. 1039, fig. 1). — A convenient ar- 

 rangement for the distillation of ether, constructed at the Oklahoma Experi- 

 ment Station, is described and illustrated by drawings. 



An electrically heated vacuum desiccator, T. B. Robertson and G. L. A. 

 Schmidt {Jour. Biol. Chem., 27 Q916), No. 2, pp. 429-431, fig. i).— A vacuum 

 desiccator, which readily accommodates a 9 in. filter, and its manipulation 

 are described. The desired temperature in the evacuated chamber is main- 

 tained by the heated vapor of dichloromethane or some other suitable com- 

 pound having a boiling point within the range of the temperature desired. 



Analysis by machinery, B. Sinkinson {Chem. News, II4 (1916), No. 2967, 

 pp. 170-172, figs. 3). — The author describes in detail an electrically operated 

 apparatus for washing precipitates which is considered to be a great time 

 saver. The device is simple in construction, has few moving parts, and can be 

 manipulated with comparatively little attention. 



A method for the determination of nitric nitrogen, F. M. Scales {Jour. 

 Biol. Chem., 27 {1916), No. 2, pp. 327-337, fig. i).— A new method for the deter- 

 mination of nitric nitrogen in which a zinc-copper couple is used is described 

 in detail. The couple used will reduce a nitrate solution at the boiling point, 

 the reduction thus proceeding during the distillation. Soil solutions high in 

 organic matter yield accurate results if clarified with alumina cream. Owing 

 to the very slight alkalinity of the reducing solution unstable organic com- 

 pounds are not destroyed in the procedure. 



Experimental data indicating the accuracy of the method are submitted. 

 A simple apparatus which yields excellent results with the method has been 

 devised and is described. 



The efficiency of the aeration method for distilling ammonia; in answer to 

 certain criticisms, P. A. Kober {Jour. Amer. Chem. Soc., 38 (.1916), No. 11, 

 pp. 2568-2572).— Contrary to the results reported by Falk and Sugiura (E. S. R., 

 35, p. 110) and others the author maintains that the distillation of ammonia by 

 aeration yields accurate results. To insure accurate results, however, it is 

 necessary to use a sufficient volume of air, as high a column of liquid with as 

 low a volume as is convenient, and an adequate excess of a saturated solution 

 of pure sodium hydroxid. Impure alkali containing or producing sulphite intro- 

 duces an error. Potassium hydroxid should not be used because the difficultly 

 soluble potassium sulphate which separates may carry down ammonia by 

 occlusion or as a double salt. 



