2 Experiments and Observations 
lings an ounce. This circumstance has hi- 
therto in a great measure precluded the use of 
the acid in the arts, and has confined the ope- 
rations of the practical chemist to a smaller 
scale than would otherwise have been the 
case. 
Though phosphoric acid, ina free state is 
not easily procured, nature furnishes us with 
a compound of that acid and lime in great 
plenty. The bones of animals, when calcin- 
ed in a red heat for some time, consist princi- 
pally of phosphate of lime. When these cal- 
cined bones are pulverized, and treated with 
sulphuric acid, the phosphoric acid is in part 
disengaged, and the sulphuric acid unites with 
the lime and forms sulphate of lime, which 
being very little soluble, is precipitated and 
leaves the phosphoric acid in the liquid, still 
united however with a portion of the lime, 
from which the sulphuric acid is not able en- 
tirely to separate it. The liquor, instead of 
being pare phosphoric acid in solution with 
water, is a superphosphate of lime in solution 
with water, or lime containing more phospho- 
ric acid in union with it than is found in the 
earth of bones. This fact was ascertained in 
the last century; and the proportion of. the 
elements in this new compound was investi- 
gated by Vauquelin. 
