33^ Mr. Hatchett's Experiments on Zoophytes, 



The solution, being filtrated, was saturated with pure ammo- 

 niac, by which, a slight precipitate of phosphate of lime was 

 separated. A large quantity of carbonate of lime was afterwards 

 precipitated, by solution of carbonate of potash. 



Part of a branch of this Isis was put into a crucible heated to 

 a low red heat. A great quantity of smoke was emitted, which 

 had the smell of burned horn ; and, after a few minutes, the 

 branch separated at the knotty joints, into as many pieces as 

 there were joints in the branch. These joints had all the 

 characters of coral ; but the whole of the membrane which had 

 invested them, as well as the knotted protuberances by which 

 they had been connected, were destroyed, by being converted 

 into coal. From this circumstance, I was desirous to examine 

 the internal structure of the membranaceous part, out of which 

 these joints of coral had been dissolved by acids. 



I took, therefore, the membranaceous substance which re- 

 mained after the first experiment, and which (as I have already 

 observed) retained the complete figure of the Isis. 



This substance being opened longitudinally, exhibited a series 

 of cavities, corresponding in form with the coralline joints, and 

 so situated, that each of these cavities extended from one bulb 

 or knot nearly to the next, throughout the whole of the branch. 



The coralline joints, when viewed separately, appeared 

 smaller in the middle than at the ends, which were terminated 

 by obtuse cones. 



In the branch, these joints were so placed, that the extre- 

 mities or cones were opposed point to point ; but were prevented 

 from immediate contact, by a gristly substance, which filled, and 

 indeed principally formed in the branch, the knot or bulb of 



