416 The late Mr. Hunter s Observations 
recent, but its having a yellow stain ; the cold may probably 
assist in their preservation. 
The state of preservation will vary according to the sub- 
stance in which they have been preserved ; in peat and clay I 
think the most ; however, there appears in general a species of 
dissolution ; for the animal substance, although tolerably firm, 
in a heat a little above ioo° becomes a thickish mucus, like dis- 
solved gum, while a portion from the external surface is re- 
duced to the state of wet dust. 
In incrusted bones, the quantity of animal substance is very 
different in different bones. In those from Gibraltar there is 
very little; it in part retains its tenacity, and is transparent, 
but the superficial part dissolves into mucus. 
Those from Dalmatia give similar results when examined 
in this way. 
Those from Germany, especially the harder bones and teeth, 
seem to contain all the animal substance natural to them, they 
differ however among themselves in this respect. 
The bones of land animals have their calcareous earth united 
with the phosphoric acid instead of the aerial, and I believe, 
retain it when fossilized, nearly in proportion to the quantity 
of animal matter they contain. 
The mode by which I judge of this, is by the quantity of 
effervescence ; when fossil bones are put into the muriatic acid 
it is not nearly so great as when a shell is put into it, but it is 
more in some, although not in all, than when a recent bone is 
treated in this way, and this I think diminishes in proportion 
to the quantity of animal substance they retain ; as a proof of 
this, those fossil bones which contain a small portion of animal 
matter, produce in an acid the greatest effervescence when the 
