134 Analysis and Valuation of Manures [212-214 



ANALYSIS OF BONE MEAL 



212. Moisture and Organic Matter.— Estimated as in 

 mineral phosphates (see paragraphs 194 and 195). 



213. Sand. — About 2 grams of the substance are 

 weighed out and dissolved in hydrochloric acid, with all the 

 precautions described in paragraph 10. Then, instead of 

 boiling down to dryness, the liquid containing the sand and 

 organic matter is treated with ammonia, citric acid, and acetic 

 acid, raised to boiling-point, and the lime thrown down with 

 ammonium oxalate, every detail as to quantities being carried 

 out as described in paragraphs 198 and 199. The precipitate 

 is collected on a filter, washed, and finally burned, as though 

 it were calcium oxalate. The organic matter will be oxidised, 

 and the precipitate may be weighed as CaC0 3 + sand. After 

 weighing, the dish is emptied into a beaker, and the CaCO ;i 

 dissolved in dilute HC1. The sand may then be filtered off, 

 washed, and weighed, as in paragraph 197. 



214. The reason for this mode of procedure is twofold : 

 Firstly. If the acid liquid containing the phosphate of 



lime, &c, in solution and the sand in suspension be filtered at 

 once, the gelatinous nature of the organic matter in the liquid 

 will often render filtration very slow. The precipitate of cal- 

 cium oxalate carries down the gelatinous matter with it, and 

 thus, after precipitation with ammonium oxalate, the liquid 

 passes through the paper quite easily. 



Secondly. Since the precipitation of phosphoric acid with 

 magnesia mixture takes some considerable time, it is advisable 

 to get it thrown down as soon as possible. By precipitating 

 lime and sand together we get the liquid for precipitation with 

 magnesia mixture at once, and thus we are enabled to go on 

 with the lime and sand estimation whilst the phosphoric pre- 

 cipitate is forming, using 40 c.c. MgCl 2 mixture. 



