253-258] Analysis of Ammonium Salts 151 



253. Estimation of Ammonia. — This may be done by 

 the soda lime method. As the substance is often damp, and 

 would give off ammonia as soon as it touched the alkaline 

 substance, it should be well mixed with gypsum before adding 

 to the soda lime. About -5 gram should be used, and the tube 

 should be about 12 inches long. 



It is very seldom that anything else is estimated in ammo- 

 nium salts, but it is sometimes necessary to estimate the 

 moisture and ' ash ' — *.*., the non- volatile matter. 



254. Moisture is estimated as usual. 



255. Non- volatile matter is estimated by weighing out 

 2 grams in a platinum capsule and heating on an Argand until 

 it ceases to fume, then weighing the residue. The burner 

 should be very low to begin with, but the temperature may be 

 increased as the operation proceeds, using a red heat to drive 

 off the last traces of volatile matter. 



ANALYSIS OF NITRATE OF SODA 



256. This substance is generally guaranteed to contain 

 95 per cent, pure NaN0 3 , the impurities being sand, together 

 with sulphate and chloride of sodium. The chlorine and 

 sulphuric acid should be determined as in paragraphs 28-31, 

 and 69-70. 



257. Nitric Acid. — Any of the methods described in the 

 chapter on nitrogen determination may be used, Ulsch's being 

 the most easily managed. 



ANALYSIS OF COMPOUND MANURES 



258. This is a somewhat comprehensive term, including 

 all kinds of special manure. Ordinarily a compound manure 

 will be found to consist of mineral or bone superphosphate 

 mixed with some nitrogenous substance. It will often contain 



