156 THE MICROSCOPE. Nov 
with the insects, ina dish of water. Wash in the water 
until the caustic potash is entirely removed. Then place 
the object in 95 per cent alcohol for twenty-four hours. 
Then soak in turpentine. The longerthe object remains 
in the latter medium the clearer and more transparent will 
it become. Itis well to allow it to remain at least twenty- 
four hours. When ready to mount, remove the object 
from the turpentine, center it ona glass slip and, under a 
dissecting microscope, carefully spread out and arrange 
the parts. In spreading, there is generally danger of 
breaking off parts and distorting the specimen. Lastly, 
mount in balsam. 
Substitute for Selenite Plate.—For use with a polar- 
izer, a cheap substitute fora selenite plate may be made 
from a well-selected mica film mounted in Canada Balsam 
ona plain glass slip and covered with a thin glass. 
SCIENCE-GOSSIP. 
Complete Set of the Journal.— We are now in possession 
of a complete set of the American Monthly Microscopical 
Journal which we can sell at a fair price. We should nat- 
urally prefer to sell itto a Public Library where many 
people could have access to it. The first five volumes are 
bound in half leather. The balance are unbound. The 
15 year index goes with the set. 
Rock Sections.—H. Rosenbusch has published ‘‘Miero-. 
scopic Physiography of Rocks” 3rd edition, and has pre- 
pared collections of thin sections for practical Microscopic 
petrographical study. ‘These collections contain thin sec- 
tions of all the more important types of rocks. To eaeh 
one 18s added a brief description. Thus one may learn to 
identify the constituents of rocks. Collections of 120 thin 
sections $38; with the Macroscopic specimens $63. Collec- 
lection of 180, $56; with specimens $98. Collections of 250 
$81; with specimens $144. These have to be imported 
from Bonn, Germany. 
