940 EXPERIMENT STATION RECORD. 



rate solutions depends upon the formation of neutral and acid calcium-amnionium 

 citrates, of which the latter only are stable. The results of a study of the behavior 

 of mono-, di-, and tri-ammonium citrates toward di-, tri-, and tetra-calcium phos- 

 phates are reported in detail. 



On the determination of citric-acid soluble phosplioric acid, W. Naumann 

 {Chem. Ztg., 21 {1903), No. 12, pii. 120, 121).— The method proposed is as follows: 

 Add \ liter of 2 per cent citric acid to 5 gm. of slag and shake in a rotary apparatus 

 for I hour. To 100 cc. of the filtered extract thus obtained add 8 cc. of strong nitric 

 acid and heat first over a small flame and then boil until the volume is reduced to 

 about 25 cc. Cool, add 25 cc. of strong sulphuric acid and 5 cc. of nitric acid, and 

 heat until white fumes begin to come off (about 10 minutes), cool in the bath, and 

 make up to a volume of \ liter. To 125 cc. of the filtered solution thus obtained add 

 35 CO. of concentrated ammonia, 50 cc. of 2-1 per cent ammonium citrate, and 25 cc. 

 of magnesia mixture, and shake for \ hour to precipitate phosphoric acid. 



The preparation of ammonium nitrate molybdic solution for the determi- 

 nation of phosphoric acid, A. Mekcier {Bui. Acad. Ruij. Behj., 16 (1902), pp. 

 389-393; abs. in Chem. CenlU., 1903, 1, No. 6, p. 5,59) .—Various methods of preparing 

 molybdic solution were compared. That preferred by the author is as follows: 

 Dissolve 100 gm. of molybdic acid in 144 cc. of 10 per cent ammonia (sp. gr. 0.9593), 

 make the volume to 500 cc. with Avater, and pour into 1 liter of nitric acid of 1.2 sp. gr. 



The rapid determination of potash in kainit, M. Passon {Ztschr.Angew. Chem., 

 15 ( 1902), No. 49, pp. 1263-1265). — The method proposed is briefly as follows: Dissolve 

 10 gm. of the salt in 200 cc. of water acidified with 5 cc. of hydrochloric acid, boil, 

 and add barium chlorid in excess to precipitate the sulphuric acid. Cool, make up 

 to 500 cc. with alcohol, cool again, make up again to the mark, and filter. To 25 cv. 

 of the filtrate add platinum chlorid solution and 125 cc. of 96 per cent alcohol, and 

 stir for 5 minutes. Filter through a Gooch filter, wash with 80 per cent alcohol, 

 then with ether, dry for 2 hours at 100° C, and weigh. Dissolve the precipitate 

 with hot water, wash, and dry as before, and weigh again. The difference gives the 

 potassium platinochlorid corresponding to 0.5 gm. of substance. 



The determination of potash in fertilizers by substituting milk of lime 

 for ammonia and ammonium oxalate as the precipitant, C. L. Hare {Jour. 

 Amcr. Chem. Soc, 25 {1903), No. 4, pp. 416-420).— Vreviously noted (E. S. R., 14, 

 p. 109). 



Modifications of an apparatus for the determination of nitrates and 

 nitrites, E. Commaxducci {Staz. Sper. Agr. Itah, 35 {1902), No. 9, pp. 747-75-2, Jig. 1; 

 abs. in Chem. Centhl, 1903, I, No. 3, p. 194). 



The volumetric determination of nitric acid, J. K. Phelps {Ztschr. Anorgan. 

 Chem., 33 {1902), p. 357; abs. in Chem. Ztg., 27 {1903), No. 15, Repert., p. 55).— Tests 

 of the accuracy of a modification of Holland's method « are reported. With proper 

 precautions, which are described, the method is said to give accurate results. 



A simple method for the quantitative determination of nitric acid in water, 

 G. FuERicns {Arch. I'hartn., -^41 {1903), No. 1, pj>. 47-53). — The method jiroposed 

 rests upon the fact that the nitrates are readily converted into chlorids by the 

 addition of hydrochloric acid and the excess of the acid may be removed by evapo- 

 ration. Thus by determining chlorin in the original solution; adding hydrochloric 

 acid, evaporating to dryness, and determining the chlorin in the residue; subtracting 

 the results of the first determination from the second and multiplying the remainder 

 by 1.525 the N^O^ present in the water may l)e obtained. 



The determination of hardness in -water, W. Peters {Ajwth. Ztg., IS {190,3), 

 pp. 25, 26; abs. fn Chem. Centhl, 1903, I, No. 7, p. 41S). —¥or waters containing large 

 amounts of magnesia in addition to lime the author uses Wartha's method. 



«Chem. News, 17 (1868), p. 219. 



