RECOMMENDATIONS FOR OFFICIAL AND TENTATIVE 

 METHODS OF ANALYSIS, AS PRESENTED AT 

 THE ANNUAL MEETING OF THE ASSO- 

 CIATION OF OFFICIAL AGRICUL- 

 TURAL CHEMISTS, NOVEMBER 

 16 AND 17, 1915. 



I. FERTILIZERS. 



GENERAL METHODS. 



1 MECHANICAL ANALYSIS OF BONE AND TANKAGE.-TENTATIVE. 

 Transfer 100 grams of the original material to a sieve having circular openings 



1/50 inch (0.5 mm.) in diameter. Sift, breaking the lumps by means of a soft rubber 

 pestle if the material has a tendency to cake. Weigh the coarse portion remaining 

 on the sieve. Determine the fine portion by difference. 



2 PREPARATION OF SAMPLE.— OFFICIAL. 



Reduce the gross sample by quartering to an amount sufficient for analytical 

 purposes. Transfer to a sieve having circular openings 1/25 inch (1 mm.) in diameter, 

 sift, breaking the lumps with a soft rubber pestle. Grind in a mortar the part re- 

 maining on the sieve until the particles will pass through. Mix thoroughly and 

 preserve in tightly stoppered bottles. Grind and sift as rapidly as possible to 

 avoid loss or gain of moisture during the operation. 



3 MOISTURE.— OFFICIAL. 



Heat 2 grams of the sample prepared as in 2 for 5 hours in a water oven at the 

 temperature of boiling water. In the case of potash salts, sodium nitrate, and 

 ammonium sulphate heat at about 130°C. to constant weight. The loss in weight 

 is considered as moisture. 



TOTAL PHOSPHORIC ACID. 



Gravimetric Method. — Official. 



4 REAGENTS. 



(a) Molybdate solution. — Dissolve 100 grams of molybdic acid in dilute ammo- 

 nium hydroxid (141 cc. of ammonium hydroxid (sp. gr. 0.90) and 271 cc. of water); 

 pour this solution slowly and with constant stirring into dilute nitric acid (4S9 cc. of 

 nitric acid (sp. gr. 1.42) and IMS cc. of water). Keep the mixture in a warm place 

 for several days or until a portion heated to 40°C. deposits no yellow precipitate 

 of ammonium phosphomolybdate. Decant the solution from any sediment and 

 preserve in glass-stoppered vessels. 



(b) Ammonium nitrate solution. — Dissolve 200 grams of commercial ammonium 

 nitrate, phosphate free, in water and dilute to 2 liters. 



(C) Magnesia mixture. — Dissolve 22 grams of recently ignited calcined magnesia 

 in dilute hydrochloric acic|, avoiding an excess of the latter. Add a little calcined 

 magnesia in excess, and boil a few minutes to precipitate iron, aluminium, and phos- 



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