NOTES AND QUERIES. 153 
then described the constant wear on the surface crust of the earth, 
principally by the action of water, as being something enormous ; 
limestone contributing its quota to swell this removal, and shewing 
that by analysis carbonate of lime constituted rather more than 50 
per cent. of this earthy matter. 
The structure of the shells of the mollusca was shewn, and also 
the structure and habits of some peculiar creatures belonging to the 
echinodermata; the paper closing with a minute description of 
probably the most wonderful piece of mechanism which in the 
economy of its nature has recourse to lime for the purpose of form- 
ing its covering with a hard shield—the “‘ Echinus.” 
The meeting concluded with the usual conversazione and exhibi- 
tion of microscopical objects. 
MountTING wITH Wax CELis.—In mounting “dry,” I have in- 
variably found a large proportion of my preparations spoilt from 
one or other of two causes. 
The most difficult one to contend with was the running in of 
the cement used to fasten the cover-glass and seal the slide up. 
The other cause was the dampness often shewn after every pre- 
caution had been taken to have both object and cell thoroughly dry 
before applying the cover-glass. 
After trying every receipt I could find, I determined to try an 
idea of my own, and which, after many months’ use, has answered 
the purpose remarkably well. No doubt others have found the 
same difficulties, so | am tempted to give my experience. 
I found a remedy for running in; it was invariably with a cement 
that caused the dampness, and vice versa, so I determined to bring 
wax to my aid. My process is to get a spirit lamp and place it 
under a dish supported on a retort stand. Into the dish I pour 
white wax or bees wax, and melt it. It requires making very hot,. 
and the lamp to be left continually under the dish. If the slide is 
to be opaque, I cut a piece of black paper to about the size of the 
cell to be made, and attach it to the slip. I then put it on the 
turn-table, and build up the cell with the hot wax. Of course it is 
allowed to overlap the paper background and the glass, and thus 
make a neat cell. It has the advantage of being built up to any 
thickness at once. ‘There is also no untidiness of the paper not 
fitting the bottom of the ordinary vulcanite cell, or if it is placed 
on the undersides of it, being scratched off. ‘Then again, if the 
background is put at the back of the glass slip, it is invariably 
bright instead of dull. When the slide is dry and ready for sealing 
up, all that is necessary is, place the cover on it and put it once 
more on the turn-table, when one turn, with the application of the 
wax brush, is sufficient to make it a permanent mount. It can then 
be finished with the usual varnishes. 
