504 EXPERIMENT STATION BECOBD. (Vol. 37 



An apparatus, which has yielded satisfactory results, and its manipulation are 

 described in detail. 



Recovery of molybdenum residues, V. Lenuer and M. P. Schvetz (Jour. 

 Indus, and Engin. Chcm., 9 (1917), No. 7, pp. 684, 685).— The authors present 

 a method for recovering molybdenum residues which consists of the precipi- 

 tation of molybdenum sulphid by hydro;;eu sulphid from a solution slightly acid 

 with nitric acid or the formation of a sulpho-molybdate solution by adding 

 hydrogen .sulphid to the alkaline solution of the " yellow precipitate " and 

 subsequent precipitation of molybdenum sulphid with hydrochloric acid. 

 The molybdenum sulphid when ignited yields MoO>. which is in a condition to 

 be readily used. 



When an acid solution is used the acidity should be kept between 0.1 and 0.4 

 per cent. In case much iron is present the sulphid should be washed with water 

 containing hydrochloric acid. When the " yellow precipitate " is dissolved in 

 alkali any iron, if present, will be precipitated as the liydroxid and can be 

 easily removed by filtration. 



Determination of total nitrogen. G. H. G. Lagers (Chetn. Wcckbl., 14 (1911). 

 No. 21, pp. 492-Jf99). — Exporiniental data on the determination of nitrogen in 

 various fertilizers containing both organic and inorganic (nitrate) nitrogen by 

 the method of Jodlbaur, the Kjeldahl method, the Kjeldahl method plus zinc, the 

 Kjeldahl method plus ferrous sulphate, and a procedure involving the Kjeldahl 

 and Schlosing methods are reported In tabular form. 



The Jodlbaur method yielded low results in samples which contained ammonia 

 or nitrates. Exact results were obtained, however, by a combination of the 

 Schlosing and Kjeldahl methods in which the sample was first treated with 

 ferrous chlorid and hydrochloric acid and then according to the regular Kjeldahl 

 procedure. 



The methods used are described in detail and the results di.scussed. 



Nitrate determinations in the presence of chlorids, W. F. Gekicke (Jour. 

 Indus, and Engin. Chcm., 9 (1917), No. 6, pp. 585, 586).— The author, at the 

 California Experiment Station, proposes a modification of the phenoldlsulphonlc 

 acid method In which the evaporation of the solution to dryness Is obvlateil by 

 the use of concentrated sulphuric acid, which Is added to the aqueous extract. 

 The addition of the sulphuric acid and phenoldisulphonlc acid to the aqueous 

 solution prevents the loss of nitrates, which in the old procedure was occasioned 

 by the addition of acid to the dry .salts after evaporation. It Is noted that the 

 temperature of the final evaporation and concentration of the aqueous solution 

 should not exceed 70' C 



Some analytical data are submitted. 



A study of the determination of potash chiefly concerned with the Lindo- 

 Qladding method, P. L. Hibbakd (Jour. Indus, and Engin. Chcm., 9 (1917). No. 

 5. pp. 50Ji-51S). — From a critical study of the method, the author has found 

 that in preparing a solution for the determination of potash considerable varia- 

 tion in the volume of water used, amount and lime of boiling, excess of am- 

 monia, and time of standing after boiling but before filtering have but little 

 effect on the results. 



Higher results and fewer Impurities In the solution are obtained by extrac- 

 tion of the material with hot water on a filter. For this extraction a tube filter 

 was found to be much more eflicient than the ordinary paper filter in a funnel. 



For correct results the Ignition of the ash must be so gradual that spattering 

 does not occur. The addition of 10 mg. of sugar during the evaporation was 

 found to be a material aid. " The final temperature need not be above a mo<ler- 

 ate red heat for a few minutes. Ixmg boating near the fusion point of the &ilts 

 causes loss of potash. A little S0« remaining as bisulphate does no harm. In 



