158 NATURAL HISTORY OF 



experiments, elaborately made, so far as we know, has yet 

 determined to what extent the criterion can be trusted. Mr. 

 Franklin Bellamy, with bis usual patient caution, submitted a 

 portion of bone from the Yealm Bridge Cave, weighing one 

 drachm ; and also a piece of bone, of the same weight, taken 

 from one by the road-side, that might have been exposed for 

 many months. Each was placed in a separate glass vessel, 

 containing diluted muriatic acid. As soon as the fossil bone 

 was immersed, a violent action commenced to disengage car- 

 bonic acid ; gradual corrosion, or removal of earthy matter, suc- 

 ceeded, and in the space of seven hours the bone waa reduced 

 to a spongy, flocculent mass, which, having become lighter than 

 the fluid, rose to the surface, in the shape of a mere pellicle. 

 This, being extracted, weighed eleven grains. In the other 

 vessel, a quiet and gradual escape of gas took place. In the 

 space of seven hours the earthy matter had been extracted to 

 one half of the depth of the piece ; and after the process was 

 complete it remained at the bottom, and retained the original 

 form of the immersed fragment. It was fibrous, soft, highly 

 flexible, and elastic, and weighed eighteen grains. By adding 

 sulphuric acid to the liquor, after removing the masses of ani- 

 mal matter from both vessels, sulphate of lime was obtained ; 

 and, when weighed, they were found to correspond very nearly 

 The fastidious caution of Mr. Bellamy did not suffer him to 

 regard this experiment as conducted with the greatest nicety. 

 At our request, he submitted a metatarsal bone of Hyena, from 

 the same cavern, to immersion in one sixth of muriatic acid to 

 five sixths of water; but in this case, after the earthy matter 

 was thrown off, the animal substance remained so abundant 

 that the bone retains its complete form, is only translucent, and 

 remains at the bottom of the liquor, as if it were a recent speci- 

 men, of which it preserves all the characters. 



Pieces of human skull, from a sub-Apennine cavern, in 

 Tuscany, probably not less than twenty-five or thirty centuries 

 old, appeared thoroughly fossilized, or rather entirely deprived 



