5o6 Experiments and Obfervatiofis on Shell and Bone. 



caufed by the proportion of the hardening fubftances relative to the gluten by which they 

 are cemented ; or by the abundance and confiftency of the gelatinousj membranaceous or 

 cartilagenous fubftance, in and on which the carbonate of lime, or the mixture of carbonate 

 and phofphate of lime, has been fecreted and depofited. Moreover as the prefence of phof- 

 phate of lime, mingled with carbonate, appears to be a chemical charadler of cruftaceous 

 marine animals, there is every reafon to conclude that Linnscus did right not to place the 

 echini among the teftacious ones. 



The prefence of phofphate of lime in the fubftance which covers the cruftaceous marine 

 animals, appears to denote an approximation to thenature of bone, which, not only by the 

 experiments of Mr. Gahn, but by the united teftimony of all chemifts, has been proved 

 principally to confift (as far as the oflifying fubftance is concerned) of phofphate of lime. 



This confideration, therefore, induced me to repeat the above experiments on the bones 

 of various animals. 



It is fcarcely neceflary for me to mention the ufual efFefts of acids on bones fteepetl in 

 them, as they are known to every phyfiologift and anatomift. 



In every operation of this nature, the oflifying fubftance, which is principally phofphate 

 of lime, is diflblved, and a cartilage or membrane of the figure of the original bone re- 

 mains ; fo that the firft origin of bones appears to be by the formation of a membrane or 

 cartilage of the requifite figure, which, when the fubfequent fecretion of the oflifying fub- 

 ftance takes place, is penetrated by, and thus becomes more or lefs converted into the ftate 

 of bone. 



It is alfo known that the nature of the bone is more influenced by the greater or lefs pre- 

 dominance of the membranaceous or cartilagenous part than by any other caufe. It is not, 

 therefore, for me to add any thing to this part ; and in refpefl: to the fubftance which is the 

 caufe of offificatien little alfo requires to be mentioned, for this (as has been already ob- 

 fcrved) is known principally to confift of phofphate of lime. 1 fliall only therefore briefly 

 mention the refult of certain experiments. 



[To be cofitifiued. ) 



VII. 



Experiments upon the Refinance of Bodies moving in Fluids. By the liev. Samuel Vince, 

 A. M. F, R. S. Plumian Pro/ejfor of JJlronomy and experimental philofopky^ in the 

 Univerjity of Cambridge *. 



XN a former paper upon the motion of fluids, I ftated the diflicuhies to which the 

 theory is fubjed, and fiiewed its infufSciency to determine the time of emptying veflTcls, 

 even in the moft fimple cafes; I alfo proved, by a£tual experiment, that in many inftances 

 tlicre was no agreement between their refults, and thofe deduced from theory. The great 



• Philof. Tranf. 1798. 



diflerence 



