1917] AGRICULTURAL CHEMISTRY AGROTECHNY. HI 



suggested, is indorsed, as well as the solution and recrystallizatlon of the pre- 

 cipitate in the presence of rather large amounts of sodium salts. 



The use of methylene blue in chemical analysis and its special application 

 for the determination of perchlorates in Chile saltpeter, A. IVIonnier (.Inn. 

 Chim. Anahjt., 22 (PJIJ), No. 1, pp. i-C).— The author has found that in dilute 

 solutions iodids, perchlorates, persulphates, bichromates, permanganates, ferri- 

 cyanids, metavanadates, molybdates, and tungstates give a precipitate with a 

 solution of methylene blue. For the distinction of ferricyanids from ferro- 

 cyanids, Iodids in iodates and periodates, persulphates in the presence of other 

 sulphur acids, and perchlorates in chlorates or other acids of chlorin the re- 

 actions are characteristic. A colorimetrlc procedure for the determination of 

 perchlorate in saltpeter which depends on the production of a violet precipitate 

 with a bronze fluorescence is described in detail. The effect of the presence of 

 iodids in the Chile saltpeter, which can easily be removed as silver iodid, is 

 noted. The other salts present in crude saltpeter are without effect on the 

 production of the color. 



Studies on the phenoldisulphonic acid method for determining nitrates in 

 soils, C. W. Davis (Jour. Indus, and Engin. Chcm., 9 (1917), No. 3, pp. 290- 

 295). — The author studied the various factors which had previously been found 

 to influence the accuracy of the results obtained by the phenoldisulphonic acid 

 procedure and found that ammonia fumes did not affect the results of the de- 

 termination. Light was found to affect the color material, so that the readings 

 to influence the accuracy of the results obtained by the phenoldisulphonic acid 

 acid had no effect on the results, nor did the temperature of the solution at the 

 time the alkali is added to develop color show any variation in results except at 

 freezing temperature, when a loss of 4 per cent resulted. Potassium chlorid 

 added just before and just after the developing of the color by potassium 

 hydroxid produced no loss of nitrates. With the use of uniform amounts of 

 phenoldisulphonic acid (2 cc.) the maximum loss of nitrates was 30 per cent. 

 When proportional amounts of the reagent were used (2 cc. for each 0.025 mg.) 

 the maximum loss was reduced to 10 per cent. 



A modified procedure in which the loss of nitrates is prevented by keeping 

 the solution alkaline during evaporation is described. The addition of two 

 drops of hydrochloric acid in a solution containing 25 parts per million of 

 nitrates caused a loss of all nitrates. By keeping the solution alkaline during 

 evaporation there was no loss even in the presence of chlorids, sulphates, and 

 carbonates. Potassium alum may be used as a flocculent in preparing the soil 

 solution without a loss of nitrates. 



The work of Lipman and Sharp (E. S. R., 28, p. 610) was checked up and 

 similar results obtained. 



A bibliography of 35 references to the literature cited is included. 



A note on the detection and estimation of small amounts of methyl alco- 

 hol, E. Elvove (Jour. Indus, and Engin. Cheni., 9 (1911), No. 3, pp. 295-297). — 

 In a study of the application of Denig&s test^ for methyl alcohol to its colori- 

 metrlc estimation the author found that by reducing the proportion of ethyl 

 alcohol from 10 per cent, as recommended by Simmonds,^ to 0.5 per cent the 

 accuracy of the method was markedly increased. 



For preparing the reagent the following procedure was found to yield the best 

 results : Two-tenths gm. finely powdered fuchsin is dissolved in 120 cc. hot water 

 and cooled to room temperature. Two gm. of anhydrous sodium sulphite dis- 

 solved in 20 cc. of water is added to the fuchsin solution, after which 2 cc. 

 hydrochloric acid (specific gravity 1.19) Is added and the whole diluted to 



»Coinpt. Rend. Acad. Scl. [Parisl, 150 (1910), No. 13, pp. 832-834. 

 •Analyst, 37 (1912), No. 430, pp. 16-18. 



