178 METHODS OF ANALYSIS. 



(c) LIME. 



Heat the filtrate from the mixed phosphates, which is acid with acetic acid, 

 to 50 C. and precipitate with ammonium oxalate. Filter, wash, ignite over a 

 Bunsen burner, and finally convert into oxid by heating over a blast lamp. 



(d) POTASH AND SODA. 



Evaporate an aliquot of the solution, prepared as described, nearly to dry- 

 ness to remove the excess of hydrochloric acid, dilute, and heat to boiling. 

 While still boiling add barium chlorid solution as long as a precipitate forms 

 and enough barium hydrate to make the liquid strongly alkaline. As soon as the 

 precipitate has settled, filter and wash with hot water, heat the filtrate to boil- 

 ing, add sufficient ammonium carbonate solution (1 part ammonium carbonate in 

 5 parts of 2 per cent ammonium water) to precipitate all the barium, filter, and 

 wash with hot water. Evaporate the filtrate to dryness, ignite below redness to 

 remove ammonium salts. Add to the residue a little water and a few drops 

 of ammonium carbonate solution. Filter into a tared platinum dish, evaporate, 

 ignite below redness, and weigh the mixed potassium and sodium chlorids. 



Determine the potash as potassium platinichlorid, using the factors 0.1941 

 for K 2 O and 0.3071 for KC1. 



13. Phosphoric Acid. 



Mix 5 grams of the material with a little magnesium-nitrate solution, dry,i 

 ignite, and dissolve in hydrochloric acid. In an aliquot of the solution de-i 

 termine phosphoric acid as magnesium pyrophosphate by the molybdate method] 

 as directed under " I. Fertilizers," page 4. 



14. Sulphuric Acid. 



Boil 5 grams of the powder gently for 1$ hours with a mixture of 300 cc 

 water and 15 cc of concentrated hydrochloric acid. Dilute to 500 cc, draw of 

 an 'aliquot portion of 100 cc, dilute considerably, precipitate with barium chlorh 

 filter through a gooch, ignite, and weigh. Direct solution of the matei 

 without burning off the organic matter was proposed by Crampton.o The dea 

 trose formed by the action of the acid on the starch of baking powders does 

 interfere with the accuracy of the process.** 



15. Ammonia. 



Ammonia alum is often an ingredient of cream of tartar substitutes and bal 

 ing powders, and ammonium carbonate is occasionally present in bakii 

 powders. Determine ammonia by distillation with caustic soda into standai 

 acid and titration. 



U. S. Dept. Agr., Division of Chemistry, Bui. 13, Part 5, p. 596. 

 Conn. Agr. Exper. Stat. Kept., 1900, p. 179. 



