and Observations on the component Parts of Membrane. 335 



The coralline then remained in a membranaceous state, and 

 retained the original figure. To the filtrated solution some pure 

 ammoniac was added, but it scarcely produced any visible effect. 



Carbonate of ammoniac precipitated a large quantity of car- 

 bonate of lime. 



Some of the Corallina Opuntia was then exposed to a low red 

 heat, in a crucible ; it emitted a smell of burned horn, and in 

 great measure retained its shape, evidently from the calcareous 

 coating. 



The burned coralline, being dissolved in dilute nitric acid, 

 deposited some animal coal. 



The clear solution afforded, by pure ammoniac, a very slight 

 precipitate of phosphate of lime ; after which, the carbonate of 

 lime was precipitated as before. 



This coralline, when treated with boiling water, like the Flustra 

 Joliacea, did not discolour it ; neither was the water changed by 

 infusion of oak bark ; but nitro-muriate of tin produced a faint 

 white cloud. 



Isis ochracea. 



When this Isis was immersed in dilute nitric acid, a consi- 

 derable effervescence was produced ; and, in proportion as the 

 calcareous substance was dissolved, the red colouring matter 

 was deposited, in the state of a fine red powder.* 



When the effervescence had ceased, (which was after about 

 three hours,) a yellowish membrane remained, which completely 

 retained the original figure of the Isis. 



* This colouring substance was not dissolved, nor changed, when nitric or muriatic 

 acids were poured upon it. It appears, therefore, to be very different from the tinging 

 matter of the Tubipora musica, or that of th&Gorgonia riobilis. 



MDCCC. X X 



