230 § 117. FERTILIZERS. 



BONE-BLACK, BONE-ASH, PHOSPHORITE. 



117. A. Bone-hlack^ after it has been used by the sugar 

 refiners, usually comes into the market as a manure. Pul- 

 verize 30-40 grms. of it for examination. 



a. Water. — Desiccate 3-4 grms. for a considerable time 

 at 150° C. 



h, Non-volatile matter.— Ignite the dried substance 

 obtained in «, and treat the residue with amnionic car- 

 bonate, to restore carbonic acid expelled during the igni- 

 tion (§ 91). 



c. Carbonic acid. — Estimate this in 3 grms. (§ 60). 



d. Nitrogen. —Burn 0.5 to 0.8 grm. with soda-lime 

 (§ 85). 



e. Phosphoric acid, etc. — Digest the contents of the 

 flask in c, after adding a little more nitric acid, several 

 hours on the water-bath ; filter the liquid into a 250 c.c. 

 flask, wash the residue with hot water, dry it at 150°, 

 weigh, ignite, and weigh again. The loss on ignition gives 

 approximately the amount of charcoal^ and the residue 

 left after ignition is to be considered as sand, though it 

 may be tested with nitric acid to see whether any more 

 is soluble. 



Dilute the contents of the flask to 250 c.c, mix all parts 

 of the solution well together, and determine phosphoric 

 acid in 50 c.c. with the uranic solution (§ 115, a). 



f. Complete analysis of the ash.— Treat a portion of 

 the solution obtained in (?, or a solution obtained in the 

 same manner, as directed in Scheme lY., § 94, taking 100 

 c.c. for a and the same for h. 



g. Chlorine may be determined in a portion of the so- 

 lution obtained in e, by precipitation with argentic ni- 

 trate (§ 63). 



h. Calcic hydrate. — It is sometimes desirable to de- 

 termine this in the bone-black. Moisten a portion of the 



