FERTILIZERS. 1 1 



(j) ALKALINE-PERMANGANATE METHOD. PROVISIONAL. 

 (For the determination of available organic nitrogen.) 



Weigh out an amount of sample containing 0.045 gram of nitrogen and trans- 

 fer to a 600 cc distillation flask. After connecting with a condenser, to which 

 n receiver containing standard acid has been attached, digest below the boiling 

 point with 100 cc of alkaline- permanganate solution (16 grams of potassium 

 permanganate and 150 grams of sodium hydroxid dissolved in water and made 

 to volume of 1 liter) for thirty minutes. Then boil until 85 cc of the distillate 

 is obtained. If the material shows a tendency to adhere to the sides of the 

 flask, an occasional gentle rotation is necessary during distillation. 



5. Potash, 

 (a) LINDO-GLADDINO METHOD. OFFICIAL. 



(1) PREPARATION OF REAGENTS. 



(a) Ammonium chJorid solution. Dissolve 100 grams of ammonium chlorid 

 in 500 cc of water, add from 5 to 10 grams of pulverized potassium-platinic 

 chlorid, and shake at intervals for six or eight hours. Allow the mixture to set- 

 tle overnight and filter. The residue may be used for the preparation of a fresh 

 supply. 



(&) Platinum solution. The platinum solution used contains 1 gram of 

 metallic platinum (2.1 grams of H 2 PtCl e ) in every 10 cc. 



(2) METHODS OF MAKING SOLUTION. 



(a) With potash salts and mixed fertilizers. Boil 10 grams of the sample 

 with 300 cc of water thirty minutes. In the case of mixed fertilizers, add to 

 the hot solution a slight excess of ammonium hydroxid and then sufficient 

 powdered ammonium oxalate to precipitate all the lime present. Cool, dilute 

 to ."00 cc, mix, and pass through a dry filter. In the case of muriate and sulphate 

 of potash, sulphate of potash and magnesia, and kainit, dissolve and dilute to 

 500 cc without the addition of ammonium hydroxid and ammonium oxalate. 



(6) With organic compounds. When it is desired to determine the total 

 amount of potash in organic substances, such as cottonseed meal, tobacco 

 stems, etc., saturate 10 grams with strong sulphuric acid and ignite in a 

 muffle at a low red heat to destroy organic matter. Add a little strong hydro- 

 chloric acid, warm slightly in order to loosen the mass from the dish, and 

 proceed as directed under (3) (a) below. 



(3) DETERMINATION. 



(a) In mixed fertilizers. Evaporate 50 cc of the solution made according to 

 (2), corresponding to 1 gram of the sample, nearly to dryness, add 1 cc of 

 dilute sulphuric acid (1 to 1), evaporate to dryness, and ignite to whiteness. 

 As all the potash is in the form of sulphate, no loss need be apprehended by vola- 

 tilization of potash, and a full red heat must be maintained until the residue 

 is perfectly white. Dissolve the residue in hot water, using at least 20 cc 

 for each decigram of potassium oxid, add a few drops of hydrochloric acid, and 

 platinum solution in excess. Evaporate on a water bath to a thick paste 

 and treat the residue with 80 per cent alcohol, sp. gr. 0.8645, avoiding the 

 absorption of ammonia. Wash the precipitate thoroughly with 80 per cent 

 alcohol both by decantation and on the filter, continuing the washing after 

 the filtrate is colorless. Wash finally with 10 cc of the ammonium chlorid 

 solution (1) (a) to remove impurities from the precipitate and repeat this 



87404 Riill. 107 OO 3 



