OF THE MICBOSCOPE. 231 



cover. The base is solid, thus giving a black back-ground of 

 rubber; around the top is a ledge fitted to receive a one-half 

 inch cover glass; this being secured by a trifle of shellac or 

 any similar cement, completes the mounting. The cell may 

 be attached to a glass slip by any cement, before or after 

 preparation. For exchanges it offers superior advantages, in- 

 asmuch as the cell, with objects enclosed, may be sent through 

 the mails independent of the glass slips, the recipient attach- 

 ing them. 



Cells similar in construction to the hard rubber cell may be 

 moulded out of melted shellac by any one who is possessed of 

 a proper die or mould. The die is easily turned out of a piece 

 of brass, and with two or three moulds of different sizes, and a 

 little shellac colored black, the microscopist may easily and 

 cheaply provide himself with a supply of cells suitable for 

 almost any object. The idea is due to Dr. Dayton, of Cleve- 

 land, and the details of the process may be found in the Ameri- 

 can Journal of Microscopy for June, 1881. 



A cell which we have found very durable, easily and quickly 

 made, and very neat, is constructed as follows: Having pro- 

 cured some good gold size and pure litharge, grind the latter 

 to a very fine powder. Mix the litharge and gold size to the 

 thickness of cream, and color either black or dark olive by 

 adding lamp-black. With this cement it is easy to make as 

 many cells as may be wanted, by laying on a ring with a brush 

 while the glass slide revolves on the turn-table. As soon as 

 the rings or cells are made, dust finely-powdered litharge over 

 them until they are covered a sixteenth of an inch deep; allow 

 them to stand a few minutes, and then shake off 1 all the loose 

 litharge by means of a few smart taps. The surface of the cell 

 will now be quite rough. Allow it to stand a few hours, and 

 then press it against a plate of glass. If this be done carefully, 

 a smooth, level, solid ring will be left on the slide. If the 

 edges should not be as smooth as they ought to be, it is easy 

 to trim them off on the turn-table by means of a small chisel. 

 Any turn-table with stout spring clips will hold a slide with 

 sufficient firmness to allow of such soft material being turned 

 quite true and smooth. Of course the tables which grasp the 

 slides by the corner are best for this purpose. Such cells, after 



