INSTRUMENT FOR MAKING CELLS OF GOLD SIZE. 
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with great facility and economy, as more circles can be cut 
from the same glass, than squares of equal breadth. 
93. Instrument for makings Cells of gold size, or of 
other fluids. In mounting microscopic objects very shallow 
cells are often required, which are most conveniently made of 
some fluid cement, as gold size, japan varnish, or some other 
similar material. This is effected by placing the slide upon a 
revolving table, and with a suitable brush laying on the cement 
evenly in a circle in the centre of the slide, as it revolves upon 
the table. 
The instrument used for this purpose consists of a small slab 
of mahogany, into one end of which is fixed a pivot, whereon a 
circular turn-table of brass, about three inches in diameter, is 
made to rotate easily, a rapid motion being given to it by 
applying the fore-finger to a milled head below the revolving 
table. A circle about an inch in diameter, traced upon the 
centre of the table, serves to centre the glass slide which is 
laid upon it, and spring-clips retain the slide on the table. A 
camel-hair pencil, dipped in the varnish to be used, is held in 
the right hand and its point applied to the slide at a proper 
distance from the centre ; the table is then rapidly rotated with 
the left hand and a ring of varnish of suitable breadth is easily 
made upon the glass. The slide is then set away to dry, when, 
if a thicker cell is required, another coat of varnish may be 
applied in the same manner. 
CATALOGUE OF ACHROMATIC MICROSCOPES. 
