RliCKNT WORK IX ACrRICULTURAL SCIl^NCE. 



CHEMISTRY. 



The determination of small amounts of potassium in aqueous solutions, 



F. K. Cameron and G. H. Failyek {Jour. Amer. Cliein. Sac, ^5 {I'JO.i), No. 10, pp. 

 1063-1073). — The method proposed is based on a suggestion of Morrell, and in })rief 

 "is to separate the potassium from other bases in the form of the potassium platinic; 

 chlorid, carefully free from an excess of reagents, take up in water and then add an 

 excess of potassium iodid, when, on standing, a l)eautiful pink or rose coI(jr develops, 

 which gradually deepens to a maximum intensity. By matching the ihtensity of 

 the color against that which would be developed in a standard solution of known 

 concentration, a measure of the amount of potassium present could be obtained." 



Tests of different modifications of the method under a variety of conditions, which 

 are reported, lead to the conclusion that the method is simple, easy of manipulation, 

 and susceptible of a high degree of accuracy in the determination of minute ipianti- 

 ties of jjotassium. 



The volumetric determination of potash as potassium bismuth thiosul- 

 phate, F. W. Kuster and M. Gruters [Ztschr. Anorgun. Chem., 36 {1903), pp. 325- 

 331; ahs. in Chem. Ceidbl., 1903, II, No. 16, p. 908). — As a result of numerous tests of 

 Carnot's method of determining potash as potassium bismuth thiosulphate the 

 authors conclude that it is impossible to obtain this salt free from the sodium salt, 

 and therefore the method is unreliable. 



On a colorimetric method for the estimation of phosphates in the presence 

 of silica, O. Schreiner {.Tour. Amer. Chem. Soc, J5 {1903), No. 10, jJp. 10.56-1062) . — 

 The method here descri))ed in full has already been noted {K. S. R., 14, p. 524). 



The reduction of nitric acid in metallic nitrates to ammonia by the electric 

 current, W. H. Easton {.Tour. Amer. CJtem. Soc, 25 {1903), No. 10, pp. IO42-IO44).— 

 A brief account is here given of a study of the precautions to be observed in using 

 Vortmann's modification « of Luckow's method, '> which is as follows: "The solution 

 of the nitrate is placed in a platinum vessel with a sufficient amount of pure copper 

 sulphate and it is then electrolyzed. It is advantageous to use a feeble current (1 to 

 2 cc. of oxyhydrogen gas per minute). When all of the copper is deposited, the 

 residual liquid is evaporated to a small bulk and the ammonia distilled off as usual." 



A small improvement in the Kjeldahl method, Gregoire and Carpiaux {Bui. 

 Js.sur. Belye Chlm., 17 {1903), No. 1, p. 36; <il>.s. in Bui. Soc. Chim. Pari.s, 3. ser., 30 

 {1903), No. 18-19, p. 1102). — It is suggested that the difficulty due to frothing in 

 case of substances rich in fat may be overcome by adding to the liquid in the distilling 

 flask a small quantity of calcium chlorid. 



The relation between the solubility of lime in the presence of alkalis and 

 the caustification of alkaline carbonates, A. D'Anselme {BuL Soc. Chim. Paris, 

 3. ser., 29 {1903), No. 18-19, pp. 936-939, fig. 1). 



«Ber. Deut. Chem. Gesell., 23 (1890), pp. 2798-2801. 

 ft Ztschr. Anaiyt. Chem., 19 (1880), pp. 324-327. 

 444 



