and Observations on the component Parts of Membrane. 333 



be repeated, as the composition of the Millepores appears to be 

 the same, with the single exception of Millepora polymorpha, 

 which afforded some slight traces of phosphate of lime. But 

 time and future experiments will shew whether this was an acci- 

 dental circumstance, or whether the Millepora polymorpha is 

 thus distinctly characterised. 



It is likewise necessary to add, that when these various 

 Madrepores and Millepores were exposed to red heat, in a 

 crucible, they emitted smoke, with the smell of burned horn or 

 feathers, became tinged with a paler or deeper gray colour, and 

 (when dissolved in acids) deposited more or less animal coal, in 

 proportion to the quantity of the gelatinous or membranaceous- 

 substance detected by the experiments lately described** 



Tubipora musica. 



Of the Tubiporce, I had only an opportunity to examine this 

 species. 



Like the former substances, it was immersed in an acid, and 

 on this occasion I employed the acetous acid. A great effer- 

 vescence was produced, and the red colour was destroyed, in 

 proportion as the calcareous part was dissolved. When the 

 solution was completely effected, some loose particles of a 

 tender membrane floated in the liquor, and were separated by a 

 filter. 



Pure ammoniac, added to the solution, produced a precipitate ; 

 which proved to be argill, accidentally lodged in the interstices 

 of the Tubipore. 



* The order in which these experiments are placed, is not that according to which 

 they were made ; but it has been adopted, because it shews more evidently the grada- 

 tions of the membranaceous substances. 



