Fossil Vegetables. ; 1 
It may be valuable to the geologist who wishes to examine fossils 
by the microscope, to have a formula of Mr. Witham’s: mode of pre- 
paring the a es for which he acknowledges himself indebted 
to Mr. Nicoll. 
He first cuts a thin slice from the fossil wood, in a direction per- 
pendicular to the length of its fibres. The slice thus obtained must 
be ground perfectly flat and then polished. The polished surface is 
- to be cemented to a piece of plate, or mirror or glass a little larger 
than itself, by means of a thin layer of Canada Balsam, applied to 
the polished surface of the slice, and also to one side of the glass. 
The slice and the glass must now be laid on a common fire shovel, 
and gradually heated over a slow fire, to concentrate the balsam. It 
will require great care to prevent the heat from becoming so great 
as to throw the balsam into a state of ebullition, for if air bubbles are 
formed in it, it will be difficult to remove them and they will prevent 
the complete adhesion of the two surfaces, when applied to each 
other. The heat of the shovel should never become so great that 
the fingers may not be’ held against it without inconvenience. With 
every precaution, some few bubbles will sometimes make their ap- 
pearance, but these may be removed by a small stick tapering to a 
fine point. When the balsam is sufficiently concentrated, and the air 
bubbles removed, the slice and the glass may be taken from the 
shovel, and applied to each other. A slight degree of pressure will 
be necessary to expel the superabundant balsam, and this will be fa- 
cilitated by gently sliding the one onthe other. By this kind of mo- 
tion, any air which might have got entangled in the balsam will also 
be removed. 
When the whole’is cooled to the temperature of the air, and the 
balsam has become solid, that part of it which adheres to the glass 
surrounding the slice, should be removed by the point of a pen knife, 
and by this operation, it will be seen whether the balsam is properly 
concentrated. If it has entirely lost its sectility, and starts off in 
flakes before the’ knife, it will be found that. the slice and glass cohere 
so firmly, that in the subsequent grinding, there will be no risk of their 
separation. If the balsam is not sufficiently concentrated, it will slide 
before the knife, and’the two bodies wil! not adhere with sufficient 
firmness. If the layer of balsam be not too thick, its due concentra- 
tion may be accomplished in four or five minutes. 
The ‘slice must now be ground down to that degree of thinness — 
which will permit its structure to be seen by the microscope. The 
