36 
Ralph, on Mounting Objects. 
inoculated with a passion for the microscope, &c._, and who 
has turned out better specimens of all kinds than I have, 
takes the following plan, for two reasons : one, that the pro- 
cess is quicker ; and the other, that there is less likelihood of 
breaking the glass. He has prepared a stout plate of brass 
about the same thickness as the glass, and this plate is per- 
forated with such sized and shaped openings as he wishes to 
make in the glass. The glass is then cemented to the plate 
with melted shell-lac or wax, and when cold, a diamond is 
drawn round the opening in the plate so as to scratch out the 
size on the glass — this is done chiefly to limit the fracture of 
the glass. He then perforates the glass, in the manner I 
have already described, with the broach, and uses the rat- 
tail files with the most unsparing vigour, so as to shiver the 
glass to pieces as far as the marked outline of the cell. This 
is done in a minute or two, and then, polishing the edges a 
little, he soaks off the glass in a solution of soda, or melts off the 
cement. I strongly recommend any microscopist who is in the 
habit of making a variety of preparations, to make trial of this 
method. The method once acquired will prove useful to him 
in a variety of ways, as the size of the cell can be enlarged 
when there is none at hand but a small one ; and too large 
cells are objectionable; cells just sufficiently large to hold 
a specimen are, to my mind, better than those which are 
more roomy. 
The question was asked me when I was in England if I 
knew how to fill a cell with Canada balsam and leave behind 
no air-bubbles. I replied in the negative, and now 1 can 
state how to accomplish this. Fill the cell with clear spirit 
of turpentine, place the specimen in it, have ready some 
balsam just fluid enough to flow out of the bottle when 
warmed by the hand ; pour this on the object at one end, 
and, gradually inclining the slide, allow the spirit of turpen- 
tine to flow out on the opposite side of the cell till it is full 
of balsam ; then take up the cover and carefully place upon 
it a small streak of Canada balsam from one end to the other ; 
this, if laid on the cell with one edge first, and then gradually 
lowered till it lies flat, will drive all the air before it, and 
prevent any bubbles from being included in the cell. It can 
be easily put on so neatly as to require no cleaning when 
dry. If the cover is pressed down too rapidly the balsam 
will flow over it and require to be cleaned off when har- 
dened, for it cannot be done safely while fluid at the edges. 
Minute specimens, I find, can be very easily mounted, 
free from air-bubbles, by placing first the object on the slide, 
and then the cover over it, and afterwards allowing the 
