714 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 



measure retained its shape, when put fnto a red-hot crucible ; but that which had 

 been steeped in the acid, curled up, and soon became a shapeless mass of coal, 

 which, by a longer continuation of the red-heat, was completely dissipated. 

 This difference appears to have been caused by the phosphate of lime, which was 

 present in the recent stem, but was dissolved and separated in the latter case by 

 the acid*. 



The experiments prove, that the gorgonia flabellum, like the gorgonia cerato- 

 phyta, consists of a horny stem, containing a certain portion of phosphate of 

 lime ; and that this stem is invested with a membrane, hardened principally by 

 carbonate of lime, which serves to cover and defend it, in the manner of a shell-|-. 



Gorgonia suberosa. — The cortical part of this gorgonia was separated from the 

 stem, and was first subjected to experiment. Some portions of this cortex were 

 immersed in dilute nitric acid ; and after an effervescence, which continued several 

 hours, a soft yellowish membranaceous substance remained, retaining the original 

 figure. The liquor decanted was pale yellow, which colour was much deepened 

 by the addition of ammonia ; at the same time a small quantity of phosphate of 

 lime was deposited. A considerable portion of carbonate of lime was afterwards 

 precipitated by carbonate of potash. Some pieces of the cortex were boiled with 

 distilled water for about 6 hours ; and to the filtrated liquor infusion of oak bark 

 was added, by which a large quantity of gelatin was precipitated. The same 

 pieces were afterwards boiled with lixivium of caustic potash, which effected a 

 perfect solution, and formed the animal soap of Chaptal ; at the same time, the 

 calcareous matter subsided to the bottom of the matrass. The cortical part of 

 this gorgonia, when put into a red-hot crucible, emitted much smoke, with a 

 smell like horn that is burnt ; after this it fell into pieces, which, being dissolved 

 in nitric acid, afforded a small portion of phosphate of lime, and a large quantity of 

 carbonate of lime. When the stem of this gorgonia was steeped during 14 or 15 

 days in dilute nitric acid, it tinged it with pale yellow. The stem after this 

 appeared more transparent and flexible, so as to approach the characters of car- 

 tilage. The yellow liquor was changed to a deep yellow or orange colour by the 

 addition of ammonia ; but did not yield any precipitate, even when carbonate of 

 potash was added. Part of a stem was cut into small pieces, and was boiled for 

 several hours with distilled water. When filtrated, the water had acquired a very 

 pale yellow tinge ; and, on the addition of infusion of oak bark, yielded a slight 

 precipitate of gelatin. Lixivium of caustic potash was then poured on the same 

 pieces; and being boiled, a thick dark-coloured viscid substance was formed, 



» These different effects are to be observed, when bone, and when the cartilage or membrane 



which remains after bone has been long steeped in acids, are subjected to a red heat. + It 



may here be proper to observe, that the membranaceous part of all these substances, such as the 

 madrepores, millepores, flustra, &c. &c. was dissolved, when these bodies were boiled with, 

 lixivium of caustic potash j and animal soap was formed. The same may also be said of shells ; and 

 Mr. Van Mons has noticed this effect on those of the oyster. See Annales de Chiniie, tome 31, 

 p. 123.— Orig. 



