146 MANUFACTURE OF FERTILIZING MATERIALS 



chlorides, the solution having been evaporated to 

 dryness and the ammonium salts expelled by heat- 

 ing to dull redness. Dissolve the precipitate with 

 10 cc. of water and add platinic chloride as in 

 potash determination, precipitating potash and 

 sodium. After evaporating dissolve the sodium 

 platinic chloride out with alcohol, leaving potas- 

 sium platinic chloride to be dried and weighed for 

 the potash determination. The sodium can be 

 determined by difference of the total weight of 

 alkalies. 



Carbon Dioxide. In five grams of the air- 

 dried soil determine carbon dioxide by mixing 

 with about four times its weight of powdered 

 borax, and fuse. Weigh and the loss in weight 

 can be taken as carbon dioxide. 



Nitrogen. Of the air-dried soil weigh out 

 three grams, place in a digestion flask, add 30 

 cc. of concentrated sulphuric acid (sp.gr. 1.84) 

 containing one gram of salicylic acid, and thor- 

 oughly mix by shaking. Heat over a low flame 

 until no further frothing, and then boil briskly 

 for five or ten minutes; now add about 0.7 gram 

 of mercuric oxide, and continue the boiling until the 

 solution is colorless; then complete the oxidation 

 by adding slowly fine pulverized potassium per- 

 manganate to the hot solution, until after shaking 

 the solution is green or purple in color. Transfer 

 the contents of the cool flask to a distilling flask, 

 using about 100 cc. of water, and add a few 

 pieces of granulated zinc to prevent bumping; 



