106 THE MICROSCOPE, 



touch its edges with cement, and let it fall gently and 

 gradually down upon the object, as represented in fig. 71 ; 

 press it lightly to exclude any excess of fluid, which re- 

 move with strips of blotting-paper, being careful to do all 

 this with a light hand, that small bubbles of air may not 

 insinuate themselves to replace any lost fluid : air-bubbles 

 are at all times unsightly, and liable to spoil an object 

 when allowed to remain. Lastly, cement the edges of the 

 cover to the bottom glass with japanners' gold-size, or 

 sealing-wax varnish, carefully drawn around the 

 edges with a camel's-hair pencil. To accomplish 

 this more effectually, Mr. J. Gorham invented the 

 " Brass cementing Pencil" fig. 72. It is a brass 

 tube, six inches long, with a conical bore, having 

 a lid to screw OD. A small portion of the cement, 

 crumbled into fragments, is shot into the tube, 

 which is then ready for use. In using this instru- 

 ment, the extremity is gently heated in the flame 

 of a spirit-lamp; and when the cement begins to 

 ooze out, holding the pencil like a pen, the point is 

 traced along each side of the cover, leaving a line of 

 cement in the angle. The cement recommended 

 by Mr. Quekett for cementing deep cells, is made by 

 melting together two ounces of black resin, one 

 ounce of bees'- wax, and one of vermilion. Mr. Hett 

 prefers dark-coloured, and old, japanners' gold-size 

 for securing the cells of his beautifully delicate in- 

 jected preparations. 1 Mr. Brooke uses Brunswick 

 black, to which has been previously added a little 

 India-rubber dissolved in mineral naphtha, to pre- 

 Fi ?9 vent its cracking when dry. A very useful cement 

 for fine work will be made by heating Canada 

 balsam until it becomes a hard resin: dissolve it in 

 ether, and it is ready for use. It possesses the advantage 

 of drying as rapidly as collodion, and, if kept carefully 

 corked, remains fluid for any length of time. 



Mr. Gorham's drawing and description of a "holder" is 

 similar to one long used by the author, fig. 73, for the 

 purpose of pressing together objects mounted in the dry 



(1) For methods of making #ood cements, consult Ure's Dictionary of Arts 

 and Manufactures. 



