and Observations on the component Parts of Membrane. 339 



some of which were polished, and deprived of their external, 

 pale red, mealy coat, whilst others were in their original state. 



A piece of the unpolished red coral being put into dilute 

 nitric acid, an effervescence immediately took place ; and, after 

 some hours, the whole of the calcareous substance was com- 

 pletely dissolved. 



The external coat retained the original figure, and appeared 

 like a pale yellow tubulated membrane, the interior of which 

 was filled with a transparent gelatinous substance. From the 

 solution I only obtained a large quantity of carbonate of lime. 



The next experiment was made in a manner exactly similar 

 to the former ; but a piece of the polished or uncoated red coral 

 was now taken. 



The effects produced by the diluted acid were the same as 

 before ; but, in the solution, some loose portions of a transparent 

 yellow gelatinous substance were now only to be seen. 



The filtrated solution was treated as in the former experiment, 

 and afforded a considerable quantity of carbonate of lime. 



As it was possible that the action of the nitric acid (although 

 much diluted) might be too powerful, I was induced to try 

 the effects of acetous acid, in which I immersed a piece of the 

 red coral in its natural state. It was gradually dissolved, with 

 a slow effervescence, and left an external tubulated membrane, 

 retaining the original form, and filled with a transparent gela- 

 tinous substance, as ip the first experiment. 



The solution, when filtrated, afforded carbonate of lime. 



A piece of the polished or uncoated red coral was treated with 

 acetous acid, in a similar manner. 



It was slowly dissolved, and left a transparent gelatinous 



