and Observations on the component Parts of Membrane. 329 



intention immediately to pursue the subject ; but I changed this 

 resolution, after a conversation with my friend Dr. Gray, Sec. 

 R. S. who suggested, that many marine substances still remained 

 to be examined in a similar manner ; and that a series of expe- 

 riments on Zoophytes (hitherto but little known in respect to 

 their component parts) would be very interesting, and might 

 probably lead to some improvement in their classification. 



I was therefore induced to make the experiments contained 

 in the following pages ; and, as the mode adopted was very 

 similar to that which was formerly pursued, it appears super- 

 fluous here to repeat the description. 



It will be proper, however, to observe, that argill is not un- 

 frequently lodged, as an extraneous substance, in the interstices 

 of many of the Madrepores, and such like bodies ; and, as argill 

 is precipitated by pure ammoniac, it became necessary not to 

 rely merely on the ammoniac, as a test of phosphate of lime. 



Whenever, therefore, any precipitate was produced by ammo- 

 niac, it was dissolved again in acetous acid, and this solution 

 was examined by the addition of acetite of lead. 



§ I. EXPERIMENTS ON ZOOPHYTES. 



Madrepora virginea.* 



This Madrepore, when immersed in very dilute nitric acid, 

 effervesced much, and was soon dissolved. 



The solution was perfectly transparent and colourless, with 



* The different species are named according to Gmelin's edition of Linn/eus's 

 Systema Natura. 



Uufi 



