204 EXPERIMENT STATION RECORD. [Vol.41 



successive measurements; and (3) that the drop method, if properly carried 

 out with calibrated pipettes, is greatly to be preferred for serological work. 



Contribution to the study of the replacement of platinum by an alloy in 

 apparatus for electrolytic analysis, P. Nicolakdot and J. Boudet {Bui. Soc. 

 Chirn. France, 4- sen, 25 {1919), No. 2, pp. 8^-86). — As a result of further in- 

 vestigation of the practicability of using an alloy in place of platinum for 

 electroytic apparatus (E. S. R., 40, p. 109), the authors state that an alloy 

 of gold and copper 9 : 1, treated for two hours with hot nitric acid and washed 

 and dried, has proved entirely satisfactory for the cathode in long continued 

 practical application. The anode of the same alloy is made in cylindrical form 

 and protected by a thin layer of electrolytically deposited platinum. 



Table of pH, H-}- and OH — values corresponding' to electromotive forces 

 determined in hydrogen electrode measurements, with a bibliography, C. L. 

 A. Schmidt and D. II. Hoagland {Univ. Cal. Pubs. Physiol., 5 {1919), No, 4, PP- 

 23-69). — ^The authors have prepared tables for the conversion of voltage into 

 hydrogen and hydroxyl-ion concentrations for both the normal and N/10 KCl 

 calomel electrode. The pH values according to the Sorenson notation have 

 also been included. The measurements and equations upon which the calcula- 

 tions are based are described in detail. 



The publication also contains a bibliograpliy of 467 refei'ences to the litera- 

 ture on hydrogen-ion concentration classified under the headings of general 

 and theoretical, biological (including blood, urine, milk, miscellaneous body 

 fluids and tissues, proteins, enzyms, and sea water), bacteriological, soil and 

 plant, miscellaneous, and indicators. 



A compilation of methods for the quantitative determination of nitrites 

 and nitrates in the presence of each other, A.. Oelsneb {Ztschr. Angew. Cliem., 

 31 {1918), No. 73, Anfmtztcil, pp. 110-112; No. 75, Aufsaizteil, pp. 178, 179; abs. 

 in Chem. Abs., 13 {1919), No. 4, pp. 295, 296).—T\\e author points out the im- 

 portance in the investigation of nitrification and denitrification processes of 

 determining the content of nitrites and nitrates in the culture solution, and dis- 

 cusses the following methods for such a determination : Colorimetric methods, 

 gasvolumetric methods, a modified volumetric method devised by the author, 

 the precipitation method, and the ester method. 



The author's method, which is described in detail, consists essentially in 

 estimating the nitrite by titration with potassium permanganate in acid solu- 

 tion and the nitrate by reduction with zinc and iron in alkaline solution. 

 Because of the volatility of the nitroiis acid, the titration is made by running 

 the solution of nitrite from a burette into a measured quantity of the acid per- 

 manganate solution diluted with water and heated at 40°. The last drops 

 are added slowly, and after decolorization the solution is titrated hack with 

 the permanganate solution. For the nitrate determination it is necessary 

 to use an amount of the sample furnishing from 10 to 30 mg. of nitrate 

 nitrogen. 



The method is considered to be well adapted for following quantitatively 

 the nitrification processes, provided ferrous sulphate is absent from the sample. 

 If citric acid is present, the nitrite should be added very slowly and the back 

 titration omitted. 



Observations on the albuminoid ammonia test, E. A. Cooper and .1. A. Rew- 

 ard {Biochem. Jour.. 13 {1919), No. 1, pp. 25-27). — Abnormal results in albumi- 

 noid ammonia determinations led to the discovery that potassium permanganate 

 may contain a stable nitrogenous impurity, which can not as a rule be re- 

 moved by prolonged boiling with alkali but which gradually decomposes when 

 the solution is considerably diluted. The authors emphasize the necessity in 



