CHEMISTRY. 409 



with slight excess of platinum chlorid until the residue solidifies on 

 cooling. From 15 to 25 cc. of acidulated alcohol prepared by pass- 

 ing dry hydrochloric-acid gas into cool 90 per cent alcohol is then 

 added to the solution, which is allowed to stand 2. or 3 minutes, with 

 occasional stirring. The solution is passed through a filter and the 

 residue washed once or twice by decantation, then thrown upon the 

 filter and washed with the acid alcohol until the excess of platinum 

 chlorid is removed. The precipitate is then washed first with ammo- 

 nium chlorid solution (200 gm. of chlorid per liter of water) and after- 

 wards with 85 per cent alcohol. 



The acidulated alcohol used in this method is prepared by gently 

 heating strong aqueous hydrochloric acid in a flask and passing the 

 liberated gas through sulphuric acid and into alcohol kept in a cooled 

 vessel. This is continued until 1 cc. of the alcohol neutralizes about 

 2^- cc. of normal potassium hydroxid. 



The method was tested with very satisfactory results on a sample of 

 ash and on mixtures of known composition containing varying amounts 

 of potassium, calcium, sodium, iron, and aluminum salts. In case ammo- 

 nium salts are present, it is recommended that they be decomposed 

 and removed by means of nitric acid, as explained in Crooke's Select 

 Methods, p. 32. 



Determination of potash in potassic fertilizers, L. Eonnet [Rev. 

 Chim. Analyt., 1897, No. 21 ; abs. in Bui. Assoc. Ghim. Sucr. et Distill., 

 16 (1898), No. 1, pp. 76, 77). — The author recommends the following 

 modification of Schloesing's method: In case of potassium chlorid 

 dissolve 50 gm. of material in water, make up to 1 liter, mix, and filter. 

 To 20 cc. of the filtrate add 10 cc. of saturated solution of barium 

 hydrate; pass carbon dioxid through the solution for a few minutes to 

 precipitate the excess of barium, and boil on a water bath until the 

 carbon dioxid dissolved in the solution and contained in bicarbonates 

 is driven off; filter, add perchloric acid, and continue the operation in 

 the usual way. 



Potash is determined in sulphate and kainit in exactly the same 

 manner, except that 40 cc. of the barium solution is used in case of 

 the sulphate and 30 cc. in case of the kainit and the precipitate is 

 washed longer. 



In the case of complex fertilizers dissolve 25 gm. in hot water. After 

 cooling, make up the volume to 500 cc, mix, and filter. Evaporate 

 100 or 200 cc. of this filtrate to dryness in the presence of 1 or 2 gm. 

 of slacked lime. Calcine at a low temperature until the organic matter 

 is destroyed, the ammonia salts volatilized, and superphosphates trans- 

 formed into insoluble tribasic phosphates. Take up in a small quantity 

 of boiling water, filter, add barium solution as long as any precipitate 

 forms, precipitate excess of barium with a current of carbon dioxid, 

 boil, and filter. Determine potash in the filtrate in the manner described 

 above. 



