112 EXPERIMENT STATION RECORD. [Vol. 41 



In conclusion the author discusses certain factors influencing the yield in all 

 forms of apparatus using platinum as a catalytic agent for the oxidation of 

 ammonia. 



Manual of the chemical analysis of rocks, H. S. Washington {New York: 

 John Wilev d- Sons, Inc., 1919, 3. ed., rev. and enl., pp. XII +271, pi. l).—Fov 

 the third edition of this manual (E. S. H., 16, p. 638), the subject matter has 

 been thoroughly revised and considerably enlarged by introducing some changes 

 in details of procedure, including new methods, treating in much greater 

 detail the methods previously described and placing more stress on the sources 

 of error both in operations and in methods. 



A ne-gr indicator for acids and bases, M. CHAxn'iEEKE (Bui. Sac. Chim. 

 France, 4. ser., 25 (1919), No. 3, pp. 118, 119).— A filtered aqueous extract of red 

 beets is said to be a very sensitive indicator for acids and bases. The extract, 

 which is a violet-red, opalescent liquid, retains its color in the presence of 

 acids and turns a deep yellow in the presence of alkalis. Test paper can not 

 be pi-epared from it as the color is not taken up by the paper. 



The volumetric determination of sulphurous acid, T. J. I. Ceaig (Jour. Soc. 

 Cheni. Indus., 38 (1019), No. 8, p. 96T).— The method described consists in treat- 

 ing a water solution of the sulphurous acid, sulphite, or bisulphite to be tested 

 with a known excess of acidified hydrogen peroxid and determining the resid- 

 ual hydrogen peroxid by titration with N/2 potassium permanganate. 



A method for the separation [and estimation] of formic, acetic, and lactic 

 acids, I. Onodera (Ber. Oluira Inst. Landw. Forsch., 1 (1917), No. 2, pp. 231- 

 259; abs. in Jour. Chcm. Soc. [London], II4 (1918), No. 674, II, pp. 461, 462).— 

 The literature on the separation of the volatile fatty acids and lactic acid from 

 mixed solutions is reviewed, and a new method is described which is said to be 

 more satisfactory than previous methods and to lend itself equally well to the 

 separation of the three acids from the fermentation products of organic ferti- 

 lizers and to the determination of lactic acid alone. 

 The essential features of the method are as follows : 



An aqueous solution of the sample is extracted with ether, neutralized with 

 alkali, acidified with phosphoric acid, and distilled with steam. The distillate 

 is conducted into alkali, partially evaporated in a vacuum, and neutraUzed 

 with sulphuric acid. The resulting sample is divided into three portions, each 

 of which is oxidized with alkaline potassium permanganate. In one portion the 

 excess of permanganate is titrated with sodium thiosulphate, the amount of 

 permanganate used determining the formic and lactic acids together. In an- 

 other portion the lactic acid alone is determined by precipitation of the oxalic 

 acid formed from it on oxidation as calcium oxalate. Acetic acid is estimated 

 in the third oxidized portion by extracting the ether, diluting the extracted 

 acid to 100 cc, and distilling the solution until 95 cc. of distillate has collected. 

 Sodium sulphite analyses, F. C. Van Heurn and W. Bertels (Arch. Rubber- 

 cult. Nederland. Indie, 3 (1919), No. 1, pp. 16; Meded. Alg. Proefstat. Alg. Ver. 

 Enibherplanters Oostkust Sumatra, Rubber Ser., No. 16 (1919), pp. 10).— The 

 results are reported of analyses of 19 samples of sodium sulphite used as an 

 anticoagulant for rul^ber latex. The analyses included the reaction on phenol- 

 phthalein and content of sodium sulphate, sodium sulphite, and inclosed water 

 and dirt. The methods employed have been noted from a previous communi- 

 cation (E. S. R., 39, p. 413). 



The purest of the samples of crystaUized sodium sulphite tested averaged 

 40 per cent of pure sulphite (theoretical 50 per cent), while the best sample of 

 the anhydrous salt contained only 80 per cent sodium sulphite (theoretical 

 100 per cent). The necessity for control of the material sold as pure sodium 

 sulphite is pointed out. 



