364 Analysis of Shells. 
store the carbonic acid, its weight was 390 grs. ‘The average of 
the two is 389.85 grs. for the earthy or saline matter in 4C0 grs. of 
the powdered shell. : 
Two parallel experiments were now performed, each with 500 
grs. of the powdered shell, exposed to a white heat in a Hessian 
crucible. Treated as before with carbonate of ammonia, they gave 
487 and 486.6 respectively, the average of which sues to 
389.44 for 400 grains. 
This differs from the results with the platinum crucible, by four 
‘tenths of a grain, caused no doubt by a small portion adhering una- 
voidably to the interior of the crucible. I therefore accept the re- 
sult given by the platinum. 
Subtracting 389.85 ers. from 400, we have 10.15 for moisture 
and animal matter. ‘The moisture was already (5) found to be 6.5 
ers. The remaining 3.65 grs. would therefore appear to be animal 
matter. By the direct process however we found the animal matter 
to amount only to 1.8 grs. It is to be observed that a small! portion 
of the difference between these two numbers, 3.65 and 1.8 must be 
ascribed to the unavoidable loss in transferring the calcined powder 
from the crucible to the capsule in treating it with carbonate of am- 
monia, and again, in the operation of weighing. ‘The remainder of 
the difference may probably arise from the disappearance of a small 
portion of animal matter by solution in the acid. We may therefore 
put down for soluble animal matter-and loss 1.85 grains. 
6. The mass remaining after the treatment with carbonate of am- 
monia, consisted as is evident from preceding experiments, of carbon- 
ate of lime, phosphate of lime and silex. The total weight of the 
mass was found to be 389.85 grains. Deducting from this the sum 
of 7.5 and 1.8 grs. the quantities of phosphate and silex, we have 
380.75 ers. for the quantity of carbonate of lime in 400 grs. of oys- 
ter shell. 
The results when summed up are as follows, 
Carbonate of lime, - - - - - 380.75 
Phosphate of lime, - - - - 7.50 
Silex aia ih accidental,) - = - - - 1.60 
Water, - - - - 6.50 
Insoluble Net matter, - - = = 1.80 
Loss, and soluble animal matter, - - - 1.85 
400.00 
