VOL. XC.] PHILOSOPHICAL TRANSACTIONS. JlQ 



immersed in acids ; but this, as well as the muriate of soda, is I believe merely 

 extraneous, and arises from small shells, parts of madrepores, and such like bodies, 

 which are often visibly lodged in the interstices of the sponges. Lastly, the 

 sponges, when boiled with lixivium of caustic potash, were completely dissolved, 

 and, like the horny stems of the gorgoniae, formed animal soap, more especially 

 when the part which is apparently insoluble in water, and which remains after the 

 gelatin has been separated, was thus treated. 



Alcyonium asbestinum. — This, after being immersed several hours in dilute nitric 

 acid, remained unchanged in figure ; a feeble effervescence was at first produced, 

 and the reddish purple colour was destroyed. The external part became pale 

 yellow, and was a soft opaque pulpy substance, within which was a stem, very 

 similar in texture, but less soft, and which still appeared of a pale red colour. 

 When pure ammonia was added to the filtrated solution, no apparent effect was 

 produced; but carbonate of potash precipitated a large quantity of carbonate of 

 lime. When a piece of this alcyonium was exposed to a low red heat, it soon 

 took fire, and emitted a smell like burnt horn ; after which it retained its figure, 

 and became white. Being dissolved in dilute nitric acid, some animal coal was 

 deposited ; and on the addition of ammonia a small portion of phosphate of lime 

 was obtained, which being separated, the carbonate was precipitated as before. 

 Some pieces of this alcyonium were digested with boiling distilled water for 6 

 hours; the liquor was then decanted, and infusion of oak bark being added, a 

 quantity of gelatin was precipitated. On the pieces of the alcyonium from which 

 the water had been decanted, some lixivium of caustic potash was poured; and 

 being boiled, the whole of the membranaceous or pulpy part was dissolved, and a 

 substance exactly similar to Chaptal's animal soap was formed, while the calcareous 

 part subsided to the bottom of the vessel. 



Alcyonium Jicus. — When the effervescence produced by pouring dilute nitric 

 acid on this alcygnium had ceased, it was found unchanged in shape, and like a 

 strong thick membranaceous substance of a fibrous texture. Pure ammonia, added 

 to the acid liquor, precipitated a small quantity of phosphate of lime ; after which 

 a copious precipitate of carbonate of lime was obtained by potash. 



Alcyonium arboreum. — This alcyonium, being steeped in the dilute nitric acid, 

 effervesced, and was acted on like alcyonium asbestinum. The calcareous pant 

 was soon dissolved ; but the form of the alcyonium remained unchanged, and still 

 appeared like a pale yellow porous substance, enveloped by a skin or epidermis. 

 Ammonia did not disturb the transparency of the solution ; but carbonate of lime 

 was obtained by solution of potash. — When exposed to a low red heat, it re- 

 sembled alcyonium asbestinum ; and a solution being subsequently made, afforded 

 some phosphate of lime, with a large portion of carbonate. As this phosphate 

 had not been discovered in the first experiment, and therefore appeared to have 

 been defended from the action of the acid by the membranaceous part, that ex- 

 periment was repeated, with this difference, that the acid was made to boil. A 



