me 
234 C.’Johnston“on Microscopical Preparations. 
slide, being careful to employ the least possible heat. Now 
carefully depress the section and withdraw every air bubble 
with a stout needle set in a handle towards the ends of the slide: 
put on the cover glass, slightly warmed, not flat, but allowing 
one edge to touch the balsam first, press out superfluous balsam, 
and the specimen is safe. The slide may now be cleaned with @ 
warm knife, spirits of wine, and ammonia. 
This communication would be incomplete without some very 
important hints concerning ‘cover glass.” It is easy to clean 
cover upon a large 
a bit of linen damp 
clean slide, and wiping one side only with : 
Ap The other side 
with aqua ammonia, and then with a dry piece. 
: erlie 
it without breaking, ges ee y too muc ape be | aid 
over the cover and upon this a thick slide; if a moderate et 
be applied to both the slides, over and beneath the ue 
direct pressure evenly exerted with the fingers (or spring clo tion 
pins) will force out all unnecessary balsam, and leave the secile 
and the protecting cover perfectly flat and unbroken. ke 
The reader will not deem me too prolix P 
first preparation, or when, after having 
scantily given in the books, he feels the nee 
cisely definite. It is certain that neither Canada b 
mastic will retain the first ground side of a specimen upon 
ae ee ea 
