WITH THE MICROSCOPE. 65 



fig. 708. When the four sides have been thus joined together, one 

 surface is to be carefully ground flat, and then cemented to the plate- 

 glass bottom. The other side, on which the cover is to be placed, 

 may be ground flat afterwards. In order to increase the strength 

 of these cells and to diminish the chance of leakage, it is well to 

 cement small pieces of glass in the corners, and narrow strips 

 outside, where the sides are attached to the glass slab, pi. XVIII, 

 fig. 109. 



These cells, of course, take some time to make, but they are exceed- 

 ingly neat, and have but one serious drawback a- slight liability to 

 leak, which is hardly to be wondered at when the number of the 

 joinings is taken into consideration. 



129. Deep Glass Cells made by bending a strip of Glass in the 

 blow-pipe flame. For some years past I have been in the habit of 

 bending a long strip of glass in the blow-pipe flame, and cementing 

 the extremities together in a similar manner whenever a cell of about 

 half an inch in depth is wanted. The ordinary plate glass is very 

 liable to crack as it becomes cool, but if flatted flint glass be 

 employed the operation is simple enough. This glass, as. well as the 

 deep glass cells above referred to, may be obtained at Messrs. 

 Powell's glass works, Whitefriars. This cell has the disadvantage 

 of not being perfectly clear. If flint glass could be flatted, ground, 

 and polished like plate, it would be of much value to those who 

 mount large objects in deep glass cells, pi. XVIII, fig. no. 



iso. Moulded Glass Cells. Of late years moulded glass cells 

 have been much employed for anatomical preparations, and the 

 absence of joints renders them preferable to built glass cells. Large 

 moulded cells are now made in Germany, the sides of which have 

 been ground and polished, and thus a preparation can be seen within, 

 almost as clearly as if the sides were composed of plate glass. These 

 cells can be obtained for a much lower price than the built cells, and 

 are, of course, not so liable to leak. They may be purchased at the 

 glass works, Whitefriars. 



131. Gutta Percha and Ebonite Cells. Gutta percha may be 

 moulded in a wooden case, and forms excellent cells where trans- 

 parent sides are not required. I have several preparations which 

 have been preserved for many years in large cells of this description. 

 Gutta percha is most useful for joining glass tubes to flat cells as may 

 be required in forming cells for special purposes, pi. XVIII, fig. 106. 



Ebonite Cells. Excellent cells may be made out of the pre- 

 paration of India rubber known as vulcanite or ebonite. They may 

 be turned to any size and thickness required. Dr. Maddox used such 

 cells in 1861. Mr. W. H. Hall also strongly recommends these cells. 



F 



