the Teeth of graminivorous Quadrupeds . 245 
bonate of lime. This error may have arisen from its solubility 
in acetous acid or distilled vinegar ; but the effects of the acetous 
acid are, in every respect, the same on powdered bone as on the 
enamel. Consequently, when enamel, or bone, is put into a 
glass matrass containing acetous acid, placed in a sand bath, 
the portion which is dissolved, is not (as has been supposed) 
carbonate but phosphate of lime ; for, if to the filtrated solution 
nitrate or acetite of lead is added, a precipitate is produced, of 
phosphate of lead, in the same manner as when nitrate or ace- 
tite of lead is added to urine. 
This mode of treating substances supposed to contain phos- 
phoric acid, as bone, &c. Mr. Hatchett has found of great 
utility ; because, by this means, he can detect phosphoric acid, 
when the substance is in too small a quantity to be examined in 
any other manner. 
Similar experiments, on the substance of teeth formed on 
pulps, and on common bone, afforded similar results. 
Mr. Hatchett considers lime and phosphoric acid to be 
the essentially constituent principles of these three different 
structures ; and, any difference that is met with, only seems to 
be that which would constitute species of the same genus, simi- 
lar to what is found in the mineral kingdom, under lime-stone, 
marble, and calcareous spar : these differ only by a small change 
in the proportions of their constituent principles, and by a diffe- 
rent arrangement of their integrant particles. 
The head of a human thigh bone was found, some years ago, 
with a thin crust of highly-polished enamel, similar in some re- 
spects to that of the teeth, upon a portion of its surface, an inch 
and half in length, and an inch in breadth ; the cartilage having 
MDCCXCIX, K k 
