On Supeiyho.sphate of Lime. 



217 



will be the use of (say) 1-lOth part more acid, supposing- the 

 bones to be as dry as they were before the fat was removed. 

 But, in point of fact, as the fat is separated, water takes its place, 

 and practically we should be sufficiently near the truth if we 

 employed the same quantity of acid to bones which have been 

 boiled for their fat as to the raw bones. But the difference is 

 considerable when much gelatine has been separated by the glue- 

 maker. I give below an analysis, made in my laboratory, of 

 boiled bones, from which the whole of the fat and a great deal of 

 the gelatine have been separated. 



Moisture 10 



Animal matter, &c. . . .16 



Sand 3 



Phosphate of lime . . . .60 

 Carbonate of lime . . . .11 



100 



This, no doubt, is an extreme case ; the animal matter not 

 being usually so much removed by boiling. The quantity of 

 oil of vitriol required to convert the phosphate of 100 lbs. into 

 bi-phosphate here will be- — 



For the carbonate . . . .11 lbs. 

 For the phosphate . . . . 33 ,, 



44 „ 



The quantity of acid to be employed more nearly approxi- 

 mates to one-half than in the former case ; but even here the 

 use of one-third of acid would give a percentage of soluble phos- 

 phate much larger than we are accustomed to meet with in the 

 best commercial samples. I shall give the composition of a 

 superphosphate which would result from the mixture of 100 lbs. 

 of the above boiled bones with 33 lbs. and 44 lbs. of oil of 

 vitriol respectively : — 



With 33 lbs. of With 44 lbs. of 

 Oil of Vitriol. Oil of Vitriol. 



Moisture ..... 



10 



10 



Animal matter . . . 



12 



11 



Sand, &c. ..... 



2 



2 



Hydrated sulphate of lime, gypsum 



42 



51 



Bi-phosphate of lime 



20 



26 



Neutral insoluble phosphate of lime 



14 



none 





100 



100 



The quantity of nitrogen in both these cases would be small, 

 the animal matter being low in percentage. The first would 

 give about Z-lOths per cent., equal to a little more than 8-lOths 

 ammonia ; and the second rather less. 



Bone-ask and Bone-black or Animal Charcoal. — Bones, when 



