24 EXPERIMENT STATION RECORD. 



clilorid and tlie whole made up to 200 cc. and filtered. Of the filtrate 

 100 cc. is taken, and when quite cold 100 cc. of ammonium-citrate solu- 

 tion and 25 cc. of magnesia mixture are added. 



The authors claim great rapidity aud accuracy. They give 28 com- 

 parative analyses with the molybdate method, none of Avhich differs 

 by more than 2 mg.— C l. parsons. 



The Stassfurt method of determining potash, A. Atterberg 

 {(Jhcm. Ztg., 20 {lSf)(J), No. 15, p. lol). — The metljod of potash determi- 

 nation recommended' by the Stassfurt Kali Works was compared with 

 the ordinary Swedish method on 10 samples of potash salts containing 

 from 12 to 10 per cent of potash. The Stassfurt method invariably 

 gave higher results than tlie other, the difference amounting in some 

 cases to 2 per cent, unless unusual care was exercised in washing with 

 alcohol. When the final precipitate was repeatedly washed and then 

 ground before transferring to the filter the results by the two methods 

 were practically identical. 



The determination of potash by the Stassfurt method, Tietjens 

 and Apel {Chem. ZUf., 20 {ISO(i), No. 21, pp. 202,203).— A reply to the 

 above article by Atterberg maintaining that it is not shown that the high 

 percentages of potash found by Atterberg in following the Stassfurt 

 method were due to any inherent defect in the method. It is suggested 

 that the impurity in the fiiml salt may have been the fault of the 

 analyst rather than of the method. 



The determination of potash as potassium platinic chlorid, H. 

 Precht {Ghem. Ztg., 20 {1S9(J), No. 22, pp. 209, 210).— In discussing 

 Atterberg's criticism of the Stassfurt method (see above) the author 

 states that it is customary for Swedish chemists to use 90 per cent 

 alcohol for washing the final precipitate, while in the Stassfurt method 

 90 to 99 per cent alcohol is preferred, and points out that he called atten- 

 tion in 1879 to the same sonrce of error as that noted by Atterberg.^ 

 He reports results of tests which indicate tliat the double salt of sodium 

 is more soluble in the stronger than in the weaker alcohol, while the 

 potassium salt is less soluble, one part of the latter being soluble in 

 42,000 parts of absolute alcohol, 37,;300 parts of 90 per cent alcohol, and 

 20,400 parts of 90 i)er cent alcohol. It is claimed that the careful 

 analyst can obtain accurate results with both 90 per cent and absolute 

 alcohol, but for the above reasons the latter is to be preferred. 



The decomposition of silicates by means of boric acid, P. Jan- 

 NASCH and O. Heidenreich {Ztschr. anorgun. Ghem., 12 {189(1), No. 5, 

 pp. 208-222). — One gram of the fine-ground silicate is carefully mixed 

 in a platinum crucible of 00 to Qi) cc. content with 3 to 4 times its weight 

 of pure boric acid, or in case of refractory silicates 5 to times, aud 

 with feldspar 8 times its weight. The mixture is then fused, special 

 precautions being taken at the beginning to prevent material from being 



'Ztsclir. angew. Cheni., 1895, p. 510. 

 ■-'Ztsclir. aualyt. C'hem., 1879, p. 509. 



