BES As 
138 THE MICROSCOPE. 
in warm weather, and therefore a very strong cement is required to 
hold them, and for this purpose I know of nothing equal to “‘ King’s 
Transparent Cement,” white or amber, which were originally prepared 
for this special purpose. A great spread of cement is not necessary 
to seal a cell ; the main point is to hold the cover glass by running 
the cement just over its edge, and far enough out on the cell or 
glass for security. One or two additional coats may be required 
after the first is hardened. If these simple directions are strictly 
followed and the work is well done there will not be much trouble 
with the leaking of glycerin cells. 
A glycerin cell may be sealed with heat for greater security, if 
thought necessary, by applying a clip of gentle pressure after the 
cover is cemented to the cell, and passing it slowly back and forth 
over the flame of a spirit lamp till the cell softens a little and the 
cover glass sinks partially into it, but this experiment is a little 
hazardous at first. 
MOUNTING IN GLYCERIN JELLY. 
Glycerine jelly answers more purposes as a mounting medium 
than any other, but it is dreaded by many on account of the difficulty 
of getting rid of air bubbles, a difficulty which may be easily avoided 
by the following method: Heat the jelly in a water bath till the 
water becomes to the boiling point, then, always working in a warm 
room, mount with it as you would with glycerin, except dipping the 
cover in fluid, being careful to remove any stray air bubbles under the 
dissecting glass before putting on the cover; for even very small ones 
cannot be depended on to disappear of their own accord. Small or 
delicate objects can be arranged and kept in place by first covering 
the bottom of the cell with glycerin jelly and placing the objects in 
it, being careful to cover them well, and leaving them to harden ; 
when hardened apply additional jelly and put on the cover. After 
standing over night in a cool place, if the jelly is of good quality, it 
may be cleaned off under water with a small paint brush and finished 
with cement. 
It is the better way to use cells for glycerin jelly mounts, 
though it is not necessary to file the surface or apply the cement 
before putting on the cover glass, or even in all cases to have them as 
deep as the object is thick; a cell prevents the cover glass from 
touching the slide at any point and thus creating a liability of form- 
ing a vacuum by shrinkage, and it makes better work every way. 
Epeartown, Mass. 
