VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 713 



possesses all the characters of membrane. But though carbonate of lime could only 

 be discovered when this gorgonia was simply immersed in acids, yet it had been 

 proved by these experiments, that a small portion of phosphate of lime is also 

 present, but so enveloped by the membranaceous and gelatinous parts, as not to be 

 dissolved by the acid menstrua, till these substances have been decomposed by fire. 

 This is not an unusual circumstance, when a very small portion of a substance 

 is enveloped by large quantities of other matter; for Bergmann, in his supplement 

 to Scheele's Essay on the Calculus Vesicae, observes, that the presence of calcareous 

 earth in certain calculi, could not be discovered in the usual manner, but by 

 operations made expressly for the purpose. 1 do not pretend to determine whether 

 the very small portion of phosphate of lime in the gorgonia nobilis is an essential 

 ingredient or not; but the mode of construction evidently proves how much this 

 gorgonia differs from the madrepores and millepores, as well as from the gorgoniae 

 about to be mentioned. 



Gorgonia ceratophyta. — When this was immersed in dilute nitric acid, an effer- 

 vescence was produced; after which, the cortical part appeared like a thin yellowish 

 membrane investing the stem, which was become transparent, and similar to car- 

 tilage. Ammonia precipitated from the solution a large quantity of phosphate of 

 lime ; and lixivium of pot-ash separated some carbonate of lime. A quantity of 

 the cortex (which had been separated from the stem by beating it between folded 

 writing paper) was steeped in the dilute acid. This solution afterwards, with am- 

 monia, scarcely afforded a vestige of phosphate of lime ; but when lixivium of car- 

 bonate of pot-ash was added, a considerable quantity of carbonate of lime was ob- 

 tained. The stem, on the contrary, when thus treated, afforded much phosphate 

 of lime, and very little of the carbonate. When burned in a crucible, it smoked, 

 and emitted a smell like burnt horn, but the figure was not destroyed; and, when 

 afterwards dissolved in the acid, it yielded the same products as before. 



Gorgonia Jiabellum. — When this gorgonia was steeped in dilute nitric acid, it 

 produced an effervescence of a short duration. The cortical part then appeared 

 like a thin yellowish membrane, which covered the stem. The latter was trans- 

 parent, and resembled softened horn of a reddish brown colour. The solution 

 afforded a large quantity of phosphate of lime, by the addition of ammonia ; after 

 which, lixivium of potash formed a less copious precipitate of carbonate of lime. 

 Some parts of the cortex were separated, by beating the gorgonia between folded 

 writing paper, and were immersed in the acid. This solution was scarcely rendered 

 turbid by ammonia ; but afforded a considerable portion of carbonate of lime by 

 potash. The stem from which the above cortical part had been separated, was 

 next examined by the dilute acid, in which, when steeped during 3 days, it became 

 soft, elastic, and in some measure cartilaginous. The acid was saturated with 

 pure ammonia, and then changed to a deep yellow or orange colour: a large 

 quantity of phosphate of lime was at the same time separated ; and but very little 

 carbonate of lime was afterwards precipitated by potash. The recent stem in great 



vol. xvin, 4 Y 



