RECENT WORK IX ACiRICULTURAL SCIENCE. 



CHEMISTRY. 



Methods of fertilizer analysis proposed by the International 

 Congress of Applied Chemistry at Brussels and Antwerp, 1894 



{Vheiti. ZUj., IS [1S94), Xo. (>!), pp. J 3:^2, IS.Qo). — Analijsi.s of nitrate of 

 soda. — Direct determination of nitrogen by tlie Schlosing-Graudeau 

 method, or by some other quick, inexpensive, and sufHciently accurate 

 jnethod is recommended. The statement of the amount of sodium 

 nitrate present shoukl be based on a complete analysis, and the chemist 

 should determine whether low contents of sodium nitrate are due to 

 adulteration or to salts which naturally occur m commeniial nitrate of 

 soda. 



Determination of phosphoric arid In general. — Small amounts of phos- 

 phoric acid should be determined by the inolybdic method. For 

 ordinary i)urposes the '•citro-mechanicar' (citric acjd) method may be 

 em])loyed. 



Determination of water-soluble and citrate-soluble -phosphoric acid. — 

 This subject was referred to an international commission for further 

 study, but (t. Masson i)roi)osed the following methods; For determin- 

 ing simply the soluble phosphoric acid in superphosphates 5 gm. of 

 superphosphate is rubbed up in a glass mortar, first witliout moistening 

 and then with 50 to 60 cc. of water. After standing a few minutes the 

 solution IS decanted through a filter. This operation is repeated twice. 

 The residue is then brought upon the filter and washed until the wash- 

 ings amount to nearly ^ liter. A few drops of hydrochloric acid are 

 added and the flask filled to the mark (250 cc.?). Fifty cubic centi- 

 meters of this solution is mixed with 30 cc. of ammonium citrate 

 (Petermann's formula') and 10 cc. of ammonia, and 30 cc. of magnesia 

 mixture is added drop by drop with continuous stirring. 



For determining both water-soluble and citrate- soluble phosphoric 

 acid in the same sample the following method is given: Of superphos- 

 phates containing over 18 per cent of phosphoric acid and of precipi- 

 tated phosphates 1 gm. is taken for analysis, of ordinary superphos- 

 phates 2 gm., and of mixed fertilizers 4 gm. The material is treated as 



' Five hundred grams of citric acid is dissolved m concentrated ammonia (0.92 

 sp. gr.y to a neutral reaction. Tlie specific gravity is brought to 1.09 at 15'~' (J. and 

 50 cc. of ammonia (0,92 bp. gi-.) added. 



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