OFFICIAL METHODS OF BELGIUM AND HOLLAND. 3<>7 



Potash — general method. — In the analysis of potash salts 10 gm. of 

 the material is placed in a liter flask with about 500 ec. of water and 

 brought to the boiling point, just enough barium chlorid is added to 

 precipitate the sulphuric acid, the volume made up to 1 liter, and lil- 

 tered.. To 20 cc. of this solution in case of sulphate and 50 cc. in case 

 of kainit 10 cc. of 10 per cent platinum chlorid is added and the solu- 

 tion evaporated to a sirupy consistency. The residue is taken up in 85 

 per cent alcohol, the crystals carefully broken, the precipitate collected 

 on a tared filter or Gooch crucible, washed with the alcohol, dried at 

 125° in an air or xylol bath, and weighed. The factor 1.94 is used in 

 calculating potash. 



Potash — special methods. — Under this head are described the Nether- 

 lands and the Corenwinder and Contamine methods. In the first, 

 which is applicable to superphosphate of potash and mixed fertilizers, 

 20 gm. of substance is boiled with water for h hour, the solution cooled, 

 and made up to 500 cc. To 50 cc. of the filtered solution at the boil- 

 ing point just enough barium chlorid to precipitate the sulphuric acid 

 is added, followed by the addition of an excess of barium hydrate. 

 The solution is cooled, made up to 100 cc, and filtered. To 50 cc. of 

 the filtrate ammonium carbonate and ammonia are added at the boil- 

 ing point until no further precipitation occurs. The solution is cooled, 

 made up to 100 cc, and filtered. Fifty cubic centimeters of the filtrate 

 is evaporated and ignited to remove ammonium salts. The residue is 

 taken up in water, filtered, and treated as in the general method. 



In the method of Corenwinder and Contamine to 50 cc. of a solution 

 of 10 gm. in 1 liter of water 1 cc. of hydrochloric acid is added and the 

 solution evaporated and ignited just below redness to drive off ammo- 

 nium salts and organic matter. The residue is taken up in water, 

 acidulated with hydrochloric acid, and the solution evaporated to a 

 sirupy consistency with the addition of 10 cc. of 10 per cent platinum 

 chlorid. The precipitate is washed with 80 per cent alcohol and then 

 redissolved in hot water, the solution being allowed to pass into 50 cc. 

 of 10 per cent sodium formate kept at the boiling point. This solution 

 is heated until reduction is complete and acidulated with hydrochloric 

 acid, a large excess of the latter being carefully avoided. The platinum 

 is collected on a filter, washed with cold water and ignited. The pot- 

 ash is calculated by multiplying the weight of platinum by 0.4835. The 

 reduction may be made by means of mercurous chlorid, according to 

 Mercier, instead of with sodium formate. 



The determination of the fineness of mineral phosphates and slags. — 

 Fifty grams of material is shaken up for 30 minutes in a sieve, the 

 meshes of which are 0.17 mm. square, the actual size of the holes being 

 0.029 mm. 



ANALYSIS OF FEEDING STUFFS. 



Preparation of samples. — Samples are ground until they pass a sieve 

 with 1 mm. meshes. 



