in the Mediterranean. 



oO 



quantity of animal matter than by calcination ; probably because a 

 part of the organic matter was dissolved in the chlorhydrid acid. 

 We know, indeed, that in the dissolution of the gelatine of bones by 

 acids, it is impossible to prevent the dissolution of a small quantity 

 of the organic substance. This method, however, served to check 

 the results of the first method, and to shew that the relative numbers 

 obtained by the two methods followed in the experiments were the 

 same. We may observe, however, that the last mentioned process 

 could not always be followed in regard to shells recently petrified. 

 These often retain a little sand between their laminfe, of wliich it is 

 impossible to deprive them. After the action of the acid, this sand 

 remains mingled with the animal matter, which, besides, is in very 

 small proportions.* 



The phosphate of lime has been treated by evaporating the solu- 

 tion of shells ill chlorhydric acid nearly to dryness, again taking it 

 up in water, evaporating it anew, and slightly calcining the residuum. 

 Taken up with water, the latter leaves a mixture of phosphate and 

 sulphate of lime. As the sulphate of lime would have rec|uired too 

 many washings to be freed from the phosphate of lime, the mixture 

 was weighed, dissolved in chlorhydric acid, and the sulphuric acid 

 precipitated by a salt of barytes. The weight of the sulphate of 

 barytes indicated the quantity of the sulphate of lime, and the dif- 

 ference between the weight of the sulphate of lime from that of the 

 primitive mixture, indicated the quantity of the phosphate of lime. 



The other constituent principles of shells have been determined 

 by the ordinary means, agitating the solution in chlorhydric acid. 



Table of Analyses of Living Shells, and of such as have been 

 petrified in Geological and Historiccd eras. 



* The animal matter obtained from shells is a-.;oted, and presents the character 

 of coagulated albumen. 



