228 § 116. PEllTILIZEliS. 



Accordiug to this tariff, the money value of 100 pounds of the super- 

 phosphate whose compositiou is given above, would be estimated as 

 follows : 



11.7 lbs. soluble phosphoric acid @ 12^ cts. $1.46 



2.19 " insoluble " " " 7>J " .32 



.41 " Litrogcn " 19>2 " -08 



$1.86 



The value of a ton of 3000 pounds, at the same rate, would be $37.20 

 in gold. 



BONE-MEAL. 



116. Bone-meal, as found in commerce, is prepared 

 either from nearly or quite fresh bones, from bones that 

 have been exposed to the air for some time, or from those 

 that have been steamed or boiled ; the first l?:ind contains 

 much fat and gelatine, and is^ usually quite coarse ; the 

 third kind has lost nearly all its fat and much of its gela- 

 tine, and is quite fine ; while the second occupies a position 

 between the other two in all respects. 



a. Water. — ^Desiccate about 5 grms., if of the common 

 kinds of steamed bone-meal, at 100°. 



h. Non-volatile matter. — Ignite the dried residue in a 

 and treat the ash with ammonic carbonate, to restore car- 

 bonic acid that was expelled by heat (§ 91, d), 



c. IVitro^en. — Burn 0.5-0.8 grms. of the finely powder- 

 ed meal with soda-lime (§ 85). 



d. Phosphoric acid. — Dissolve 3-4 grms. of the ash 

 obtained in h in as little nitric acid as possible, Avith the 

 aid of heat; filter the solution into a 250 c.c. flask, wash 

 the sandy insoluble residue, ignite, and weigh it. Fill the 

 flask with distilled water up to the 250 c.c. mark, mix its 

 contents well together, and determine phosphoric acid in 

 50 c.c. of this solution, with the standard uranic solution 

 (§ 115, a). In order to saturate the free acid, it will be well 

 to add 20 c.c. of the sodic acetate. If a coarse, splintery 



