CHEMISTRY. 103 



{lS9f!), No. 4, p. 20i). — The following modification of TMiircker's method 

 hiisbeeii found by the author to give good results iu the analysis of 

 phosphates: 



"The amniouiacjil solutidii of the aminouium phospho-molybdate obtained in the 

 ordiiiiirv \\ay from i gm. of ])hosphorite is freed from the surplus of ammonia by 

 eithci- boiliuji- or heating on the water bath, and to the neutral solution, after cooling, 



2 drops of magnesia mixture is added, which should, after some stirring, produce 

 a precipitate. Should this, however, be delayed, 1 or 2 drops of concentrated ammo- 

 nia is added, always stirring until the precipitate shows itself. Then the precipi- 

 tation is continued to the end in the ordinary way l-j- the addition of the necessary 

 magnesia mixture. After, say half an hour, ammonia is added as usual in the execu- 

 tion of the Miircker metliod. Th(i i)recipit:'.te of ammonium-magnesium phosphate, 

 after washing with dilute ammonia, may for convenieme sake be moistened by a 

 coucentri'tcd ammoniacal solution of ammonium nitrate, as recommended by Glaser 

 in the execution of the citric method. The ignition is done over the Buusen burner 

 until the filter is burned and liually to constancy of weight over the gas burner." 



It is claimed that control analyses with ^ gm. of pure silver phos- 

 phate "have demonstrated the absolute correctness of this moditica 

 tiou of tlie Miircker method." 



The molecular weight and formula of phosphoric anhydrid 

 and of metaphosphoric acid, W. A. Tilden and 11. E. Barnett 

 {Jour. Cheni. i^oc, lb96, Mar., j)}). 154-160, Jig. 1). — A number of deter- 

 minations by the Victor Meyer vapor expulsion process of the vapor 

 density of carefully prepared samples of })]»osphoric anhydrid are 

 reported which indicate a molecular weight corresiwuding to P40in. 

 In the preparation of the phosphoric anhydrid it was observed that the 

 metaphosphoric acid iormed was quite readily volatile. The results of 



3 series of experiments on the vapor density of this compound indicate 

 "that although the composition of metaphosphoric acid varies a little, 

 the vapor of this substance consists chiefly of dimetaphosphoric acid 

 H2P20t;, which is apparently liable to undergo i)artial di.':sociation at a 

 high temperature and even during ebullition to part with a small 

 quantity of water. 



The determination of potash, F. T. B. Du Pni: {Chcm. Ztg., 20 

 {1890), No. 31, p. 305). — In view of a suggestion to change the factor 

 for calculating potash in potassium platinic chlorid, the author rei)orts 

 work by himself and others, which shows that the results of the deter- 

 mination of potash by any method are usually variable, and that accu- 

 rate results can only be obtaiticd by determining the factor which is 

 applicable to the particular set of conditions under which the analyst 

 works. 



Determination of potash, A. Prager {Chem. Zfg., 20 {1896), No. 

 27, p. 269). — The method proposed for the determination of potash in 

 combination with sulphuric *acid is as follows: An aliquot part of the 

 potash solution is precipitated with chlorid of barium in the usual 

 manner, using the minimum excess of the chlorid. The filtrate t!iom 

 the sulphate of barium is diluted to 75 cc, platinum chlorid added, and 

 the solution evaporated on a water bath kept below the boiling i)oiut. 

 509G— No. 2 2 



