Analysis of Shells. 365 



One hundred grains of oyster shell will therefore give, 

 Carbonate of lime, - 

 Phosphate of lime, - 

 Silex, - - 



Water, - - - - - 

 Insoluble animal matter, - - - 0.45 



Loss, &c. - - - - - - v 0.46 



95.18 

 1.88 

 0.40 

 1.62 



100.00 



As the quantity of carbonate of lime above stated was estimated 

 by deducting the ascertained amount of certain ingredients, it was 

 deemed important to verify the calculation by a direct determination 

 of the proportion of the carbonate. Accordingly 100 grs. of shell 

 were treated with muriatic acid, — filtered and then supersaturated 

 with ammonia to precipitate the phosphate of lime. The liquid fil- 

 tered from the phosphate was then acted on by oxalic acid and the 

 oxalate of lime as before converted into carbonate. The carbonate 

 when dried agreed in weight very closely with the computed number, 

 being very slightly more than 95.18 grains. 



The oyster shell is therefore a carbonate of lime, nearly in a state 



of purity, and it is in this light that it should claim attention either in 



agriculture or medicine. 



The scollop shells (Pecten JefFersonius and P. Madisonius) of the 



marie beds of the southern states of which I have recently analyzed 



several specimens, yield a larger proportion of animal matter than 



the recent oyster shell, and indeed in many instances these shells 



would seem to have sustained no loss of this or in fact of any of 



their original constituents. 



The large variety of coral (Astrea) which belongs to the same 

 marl, contains a very minute proportion of animal matter, and nearly 

 the same per centage of phosphate of lime, as the oyster shell. 



Further observations upon the chemical structure, of our living 

 and fossil shells I reserve for a future communication. 



