712 
SUPERPHOSPHATE OF LIME. 
each; cattle, £6 10s.; sheep, 22s.; and pigs, 25s. each. In 
1855, the total value was £33,053,478 ; in 1856, £33,120,220; 
in 1857, £33,700,916; in 1858, £34,334,890; in 1859, 
£35,368,259; and in I860, £33,839,899. The difference in 
value between 1859 and I860 showed a decrease of £ 1,528,360. 
SUPERPHOSPHATE OE LIME. 
To obtain the above compound, now so largely used as an 
artificial manure, Mr. J. D. Bryant has patented a process 
which, says The Chemical News , “involves an exceedingly inge¬ 
nious idea, and although we fear there will be practical diffi¬ 
culties in carrying it out, we sincerely trust they will be over¬ 
come so as to enable the patentee to work his process on the 
large scale. All who have made bone superphosphate, or 
who have in any way given their attention to it, are aware 
that it invariably contains a considerable quantity of gypsum; 
moreover it has hitherto been impossible, from the very 
nature of the raw material, to prevent its formation. Burnt 
bones consist principally of carbonate and phosphate of lime; 
now it is evident that on treating such a mixture with sul¬ 
phuric acid in excess, the whole of the carbonate of lime will 
be converted into sulphate, and, moreover, that until the car¬ 
bonate is decomposed, the acid will be unable to render the 
phosphates soluble. Mr. Bryant has applied himself to over¬ 
come this difficulty by burning the bones at such a tempera¬ 
ture as to causticise the carbonate of lime, and then dissolve 
the quicklime out with—1st, rain, river, or spring water; 2d, 
water mixed with acids, or combined with alkaline or mag¬ 
nesian salts from chemical manufactories or other sources ; 
3d, water mixed with bittern, or the refuse of sea-salt masalt 
manufactories; 4th, sea-water in its natural state, and this 
latter will, according to the patentee, be generally found the 
most economical solvent for the purpose. 
“ When bittern is employed, or even sea-water, a double 
decomposition takes place between the chloride of magnesium 
and the lime, chloride of calcium remaining in solution, and 
magnesia being precipitated. The patentee gets over this 
apparent difficulty by availing himself of the levity of mag¬ 
nesia as compared with phosphate of lime. The stream of fluid 
is so managed as to wash away the former and leave the latter. 
“ Undoubtedly the processes patented involve more than 
one chemical and mechanical difficulty, but from the general 
tenour of the specification we doubt not that the patentee is 
capable of successfully grappling with them. The impor¬ 
tance of the subject is so great that we hope he will be suc¬ 
cessful.” 
