(16 j THE GEELONG NATURALIST. 
than others. The glasses on which. objects are mounted are 
usually crown or sheet, but in slips 8in. x lin. 
Having chosen a glass slide, clean and polish with a piece of 
chamois leather, and get the centre by means of a piece of paper of 
exactly the same size as itself âq in the centre of which a hole has. 
been cut. 
Place the paper under the slide, and having removed the object 
to be mounted from the turpentine in which it was soaked, lay it om 
the slide on the spot over the hole in the paper or card underneath. 
Then take up a small GERA of the Canada balsam on the point 
of a large needle and drop it on the object. Slightly warm it over 
the spirit lamp to diffuse the balsam and to cause it to thoroughly 
penetrate the object, and immediately cover tbe object with one of 
the circles of thin glass. In this, care must be taken to bring the 
edge of the circle down first, and let the other fall slowly on the 
object. It requires some practice to keep the specimen in the 
centre of the circle. 
` Notwithstanding very great care in manipulation, air-bubbles 
will appear. These may, however, be removed by gently warming 
the under part of the slide over the spirit-lamp, when the bubbles: 
will leave the object and travel towards the edge of the ciréle, — In 
most cases they will entirely disappear as the balsam becomes firmer 
and drier. When thoroughly dry, the superfluous balsam which 
surrounded the edge of the circle may be scraped off with a penknife: 
and the edge of the circle may be rendered smooth by rubbing 
gently -with an old silk handkerchief moistened in turpentine. 
Some cover their slides with fancy paper (which saves the trouble of 
grinding the edges) and rub them with a file, and thus prevent 
them from cutting the paper. 
Objects mounted either in Canada balsam or in fluid must 
always be kept in a horizontal position. In mounting objects in 
balsam care must be taken to have specimens quite dry before 
soaking them in turpentine. | Objects mounted in cells, on the other: 
hand, should be saturated with the mounting fluid before being 
gnally secured. . 
There are some objects much more difficult to prepare than 
others, and the beginner must not be discouraged by a few failures. 
Let his motto be “Forward!” and practice will soon teach him the 
best way of managing intricate and difficult objects. ^ One point 
must be observed—there must be no dust flying about, and every- 
thing must be kept scrupulously clean, since the smallest speck of 
