362 Analysis of Shells. 





sieve. 



and which is equally inconsistent also with the experiments about to 



be detailed. 



The shells submitted to analysis were of middle size, had been 



some weeks opened, and were perfectly dry, and as clean as they 



could be made by washing in cold water with friction. There was 



therefore a small portion of the dark crust adhering to their outer 



surface, and this was intentionally permitted, to remain. It did not, 



however, form one half per cent, of the entire mass. 



The shells were finely pulverized and then sifted through a very 

 fine 



1. Two specimens of the powdered shell each 200 grains, were 

 enclosed in small glass matrasses of known weight ; these were pla- 

 ced on a sand bath and exposed sometime to a temperature of 200°, 

 this having been found by previous trial, to be about the highest heat 

 which the substance would bear without a change of color indicative 

 of incipient decomposition. A considerable dew collected in the long 

 neck of each vessel, which by continuing the heat was all finally ex- 

 pelled. — Each flask with its contents was now accurately weighed*. 

 The difference of weight, now and before heating gave the amount 

 of moisture which in one instance was 3 grains, in the other 3.2 

 grains, giving an average of 3.1 grains in 200 grains of 1.55 per cent. 

 Results almost precisely the same were obtained in a similar experi- 

 ment afterwards. 



2. 400 grains of the powder were now digested in pure muriatic 

 acid. Two filters were prepared, dried on the sand bath and coun- 

 terpoised. Through one of these the liquid was filtered, the insolu- 

 ble matter carefully washed, and the filter and contents dried. Both 

 filters were now exposed to the sand bath to bring them both to the 

 same degree of dryness, and then placed in opposite scales. The 

 excess of weight arising from the insoluble matter on the filter was 

 3.4 grains; of this obviously only a part was animal matter, and it 

 became a matter of delicate experiment to determine accurately how 

 much. 



3. The filters were successively burnt in a platinum crucible, un- 

 til nothing but a white ash remained, 



The results weighed as follows 

 That of the filter containing the residue 2.2 grains, 

 That of the filter alone, - - 0.6 grs. 

 The former residue, viz : 2.2 grains, obviously consisted in part 

 of the proper ashes of the filter itself. This, amounting to 0.6 gr. 



