92 CHEMISTRY OF THESE BONES. 
to offer a modified opinion. That it is somewhat 
lessened in quantity in all bones of this class and 
date, I have no doubt ; but, I also think that there 
are differences dependent on the bone selected for 
examination, on its being entire or fractured, on its 
situation in the cave, and so forth. If you experi- 
ment on a small fragment, the result will seem to 
bevery different from what it is when experimenting 
on an entire bone, at least so far as regards the 
ordinary method.of employing muriatic acid to dis- 
solve the earths and exhibit the remaining animal 
portion. Thus, when by experiment I endeavoured 
to determine the comparative difference between 
these, and bones of ordinary occurrence, I found 
that after selecting a fragment of fossil bone and a 
piece that had lain exposed on the high-road for 
some months, each weighing a half drachm, and 
putting them in maceration in glass vessels, violent 
and rapid escape of carbonic acid gas, due nd doubt 
to the imbibed calcareous matter, proceeded directly 
on the fossil piece being immersed ; gradual corro- 
sion, or rather gradual removal of the earthy 
portions was soon evident, and in the space of 
seven hours, nothing remained of the original frag- 
ment but a small spongy, flocculent mass, or pellicle, 
weighing eleven grains. On the contrary, the other 
fragment gave off slowly and deliberately gaseous 
matter; the process of removal of the earths was 
not finished for a very long time, and in the end, 
the original form ofthe immersed piece was retained ; 
it was soft, fibrous, flexible, and elastic, and weighed 
eighteen grains. But again, my brother finds that 
in exhibiting the animal form of bones, no external 
difference is observable between specimens of this 
kind, derived on the one hand from a phalangeal 
bone of the fossil hyzna, and on the other from 
any common bone. The first seems to exhibit the 
fact as well as the other; but I decidedly think 
