674 



when fragments of these bones were acted upon by heat under a 

 test-tube. 



With respect to the second great class in which the animal matter 

 has been removed, the following cases were mentioned : — Portion of 

 the external and internal parts of a mammoth tusk from Siberia, did 

 not blacken by heat, and dissolved completely in muriatic acid. The 

 internal part of a tusk from Ohio gave the same results, but the ex- 

 ternal part was found to contain a considerable proportion of animal 

 matter. Inbones from the crag, the animal matter had been abstracted. 

 Human bones which had been long buried were found to be in the 

 same state. 



The paper concluded with the following remarks. As the different 

 states, Ln which animal matter is found in fossils, pass insensibly into 

 each other, and as many of the changes occur in church-yard and other 

 bones, it follows, that no extraordinary circumstances are requisite 

 to produce these alterations ; but that they may be effected by the or- 

 dinary processes of putrefaction. Even the carbonization of animal 

 matter may be accomplished by similar processes without the aid of 

 heat, as bones become black by being macerated too long. It is also 

 to be observed, that the parts of animals preserved in the fossil state, 

 are those which longest resist putrefaction. It having been likewise 

 shown that the degree of change does not depend upon the age of 

 the bed in which the fossil occurs, it is a curious subject of inquiry 

 for the geologist to ascertain how far the conditions necessary to pu- 

 trefactive air, a certain temperature and moisture, were present in 

 those strata, in which the change has been great ; how far they were 

 absent in those, in which the change has been small. 



