324 MOUNTING MICROSCOPIC OBJECTS [Ch. X 



§ 503. Preparation of mounting cells. — (A) Thin cells. These 

 are most conveniently made of some of the cements used in micros- 

 copy. Shellac is one of the best and most generally applicable. To 

 prepare a shellac cell place the slide on a turn-table (fig. 191) and 

 center it, that is, get the center of the slide over the center of the turn- 

 table. Select a guide ring on the turn-table which is a little smaller 

 than the cover-glass to be used, take the brush from the shellac, being 

 sure that there is not enough cement adhering to it to drop. Whirl 



Fig. 191. Turn-table for Making Cells and for Sealing Cover-glasses. 



Hand Rest The metal plate supporting the hand that holds the brush. It can 

 be raised or lowered by means of the screw underneath is). 



sc Spring clips for holding the slide in place. 



gc Guide circles to aid in centering the slide or the mounted object. 



mc Milled circular disc by which the turn-table is whirled when the ring of 

 cement is being painted around the cover-glass or the mounting cell. 



the turn-table and hold the brush lightly on the slide just over the 

 guide ring selected. An even ring of cement should result. If it is 

 uneven, the cement is too thick' or too thin, or too much was on the 

 brush. After a ring is thus prepared remove the slide and allow the 

 cement to dry spontaneously, or heat the slide in some way. Before 

 the slide is used for mounting, the cement should be so dry when 

 it is cold that it does not dent when the finger nail is applied to it. 



A cell of considerable depth may be made with the shellac by adding 

 successive layers as the previous one dries. 



(B) Deep cells are sometimes made by building up cement cells, but 

 more frequently, paper, wax, glass, hard rubber, or some metal is 

 used for the main part of the cell. Paper rings, block tin or lead 



