AGKICULTUEAL CHEMISTRY AGROTECHNY. 609 



well stirred with water. It is then filtered and washed to remove as much as 

 possible of the chlorids and dried at room temperature. The filtrate from 

 this recovered product may be treated for a further recovery of ammonium 

 molybdate, the impure product being purified by recrystallization from boiling 

 water to which has been added some 10 per cent ammonium hydroxid. 



A similar procedure for the recovery of molybdic acid from the residues of 

 the Lorenz (B. S. R., 13, p. 14) and Pemberton methods is also outlined. 



Examination of water for sanitary and technic purposes, H. Leffmann 

 (PJiiladcIpJiia: P. BlaJciston's Soil d Co. [1915}, 7. ech, rev. and enl., pp. XVI-{- 

 140, figs. 6). — The seventh edition of this worl^, revised and enlarged. The 

 purpose of the volume, as stated in the preface, is to furnish the commercial 

 and works-laboratory with a summary of the best processes for ascertaining 

 the sanitary and technical value of a water sample. The procedures have been 

 brought into general agreement with those recommended by the American 

 Public Health Association. 



Investigations on the acid and alkali content of soils, A. Stutzee and W. 

 Havpt (Jour. Landw., 63 (1015), No. 1, pp. 33-45). — The great influence of 

 free acid in the soil on the crop and the soil bacteria, and also on the chemical 

 changes produced in the so'l, is pointed out. The method for soil acidity of 

 Tacke and Siichting (E. S. R., 21, p. 9) was not found to be as satisfactory 

 as reported by other workers. 



For the qualitative determination of acidity in the soil the methods proposed 

 by Baumann and Gully (E. S. R., 19, p. 1008), Loew (E. S. R., 21, p. 703), and 

 Daikuhara (E. S. R., 31, p. 618) have been tested and found to be satisfactory. 

 A quantitative method for the determination of acidity in soil, based on the 

 qualitative test of Baumann and Gullj', has been devised and is outlined in 

 detail. Experimental results indicate the applicability of the method. 



A method for the determination of water-soluble alkali, based on the same 

 principle, is also described. The presence of carbonates does not necessarily 

 indicate the absence of acids. • A soil which requires more than 200 mg. of 

 suphuric acid for neutralization per kilogram is considered strongly alkaline. 

 From experimental data the authors conclude that it is impossible to determine 

 the acidity of a soil by treatment with dilute alkali and therefore recommend 

 the iodid-iodate method which they have devised. 



A proposed rapid method for the analysis of limestone for agricultural 

 processes, A. S. Behkman {Jour. Indus, and Engin. Chem., 8 (1016), No. 1, pp. 

 42-45). — A tentative "differential" method for the agricultural analysis of 

 limestone is proposed. 



The procedure outlined is to dissolve the sample (1 gm.) in 50 cc. half- 

 normal hydrochloric acid, add a few drops of 8 per cent hydrogen peroxid, and 

 heat on the water bath at S6° C. for 30 minutes. The flask and contents are 

 then cooled, 5 gm. of ammonium chlorid added, and the iron and aluminum 

 precipitated with 25 cc. half-normal ammonium hydroxid. After standing for 

 15 minutes the precipitate is filtered and washed with a neutral 10 per cent 

 solution of ammonium nitrate, ignited, and weighed. This weight represents 

 the insoluble residue, plus iron and aluminum. The filtrate and washings are 

 then titrated with standard half-normal hydrochloric acid, using methyl orange 

 as an indicator. From the amount of hydrochloric acid used to put the carbon- 

 ates in solution and from the total carbonates (original sample, minus insolu- 

 ble residue and ammonia precipitate) the percentages of calcium and magne- 

 sium carbonates can be calculated by two simultaneous equations. The theory 

 of the calculation is explained in detail. 



