68 THE MEDALS OF CREATION. 
when the emery ceases to act, the muddy matter remaining 
should be removed, and a fresh portion of emery applied; 
this must be repeated until the surface of the slice is per- 
fectly flat ; a sheet of copper must then be substituted for 
the lead, and the fossil ground as smooth as possible by 
flower of emery, freed from its coarser parts. The surface 
may then be polished by friction, with crocus or rotten stone, | 
on a transverse section of any soft wood.” * 
* Mr. Witham, Observations on Fossil Vegetables. 
