Cft Shell and Bone. 3^^ 



78 Grains of the hora of the chamois afforded only 0,50 



of rcfidauni ; and 500 grains of tortoife-ftiell yielded not 



more than 0,25 of a grain, of which lefs than half was 



phofphat of lime. 



Now, it muft be evident that fo very fmall a quantity can- 

 not influence the nature of the fubftances which afforded it; 

 and the fame may be faid of fynovia, 480 grains of which 

 did not yield more than one grain of phofphat of lime. 



This fubftance is undoubtedly various in its proportions 

 in all thefe and other animal fubftances, arifing, probably, 

 from the age and habit of the animal which has produced 

 ' them ; but I believe that I may at leaft venture to place 

 fome confidence in the foregoing experiments, as feveral 

 others, made fmce the above was written, have tended to 



confirm them *. 



In the courfe of making the experiments which have beea 

 related, I examined the foffil bones of Gibraltar, as well as 

 fome gloffupetrse, or {bark's teeth. The latter afforded phof- 

 phat and carbonat of lime ; but the carbonat of hme was 

 vifibiy owing principally to the matter of the calcareous 

 ftrata which had inclofed thefe teeth, and which had infinu- 

 ated itfclf into thefe cavities, left by the decompofition of the 

 original cartilaginous fubftance. 



The bones of the Gibraltar rock alfo confift principally of 

 lime, and the cavities have been partly filled by the carbonat 

 of lime which cements them together. 



Foffil bones referable bones which by combuftion have 

 been deprived of their cartilaginous part; for they retain the 

 figure of the original bone without being bone in reality, as 



• Thefe experiments were repeated on bladders, which I chofe in pre- 

 ference to any other membrane, as not being liable to ofiification, and 

 therefore likely to contain very little or no phofphac of Jjme. 250 grains 

 of dry hog's bladder, after incineration, left a refiduum, the weight of 

 which did not exceed .-50th of a grain. This was diflfolved in diluted 

 nitric acid ; and upon adding pure ammonia, fome faint traces of phof- 

 phat of lime were obfe. ved. Now, as 250 grains of bladderd.d not afford 

 more than .-50th of a grain of rcftduum, of which only a part confifted 

 of phofphat of lime, there is much reafon to regard this experiment as an 

 additional proof that the phofphat of lime is not an elTential ingrcOient of 

 membrane. 



Vol. VI. 3 A «n« 



