H. Goadby on making wet Preparations of Animal Substances. 25 
4 a we 
and make as near approach to contact with the lower glass as is 
compatible with the thinest layer of glue. The four pieces of 
the cell having been cemented to the slide and to each other, its 
position can be readily adjusted to the center by the aid of the 
cross. Should the glass become a little too cool and the glue set, 
replace it on the iron plate and complete the adjustment. 
Before the glass and the glue become quite cold and hard, it is 
desirable to remove the superfluous glue which holds most perti- 
naceously when cold: the best form of instrument for this. pur- 
pose is the lozenge-shaped tool used by engravers, keeping the 
point close to the sides of the joint, or a knife point may be used, 
taking care not to scratch the glass. Asa rule, it must be borne 
in mind that, whenever a cell consist of more than one piece of 
glass, it should be ground flat on the pewter plate before it is fit 
to be trusted: the slightest inequality, either in the substance of 
the glass at one end, or in the layer of the marine glue, will pre- 
Vent the possibility of making a good joint hereafter with the 
top glass or cover. 
To clean the glass perfectly I use a small piece of cotton wool 
gathered into a knot, held by a pair of strong steel forceps, and 
a drop or two of liquor potasse, or a saturated solution of caustic 
potash, which softens the marine glue and admits of its removal. 
must eu not to allow the potash to remain in contact 
with the - as it decomposes the glue, and will render the 
joints unsound. The glass should be well rinsed in a large quan- 
tity of clean water to remove the potas 
A top glass or cover must now be cut for the cell, and this 
should be somewhat smaller than the outer diameter of the cell 
on all sides to allow room for the cement. The edges of the 
cover, and the surface of the cell should be painted with the naph- 
tha solution of marine glue; and the cell will then be ready for 
the reception of the preserving fluid, and the preparation. It is 
best to fill the cell over some other vessel to catch the excess of 
fluid that is sure to run over the sides; a small, shallow dish or 
saucer will answer this purpose; and if the cell be supported 
upon a level something placed in the dish, the better, as the ope- 
rator will have his hands at liberty. 
Having filled the cell with fluid, take a short but strong cam- 
el’s (or badger’s) hair pencil and rab the fluid into the corners, 
the sides of the cell, and even the bottom glass, for this 
