270 MANIPULATION. 



CHAPTER III. 



METHODS OF CEMENTING CELLS. 



There are three principal methods of mounting microscopical 

 preparations : — first, in the dry way ; second, in some kind of 

 preservative fluid, such as spirit and water, or Goadby's or 

 other solution ; and third, in Canada balsam. In the first 

 method, aU that is generally required is a slip of glass or a 

 slide (as it is commonly termed), and a cover of thin glass ; 

 but, in the second method, when the object is of any thickness, 

 the fluid requires to be contained in some kind of reservoir, 

 which is most frequently made of glass, and is called by micro- 

 scopists a cell. Of these, various shapes and sizes wiU be found 

 necessary, but as aU require to be fastened to a slide, by means 

 of some kind of cement, it wUl be as well here to describe the 

 most approved methods of conducting the operation. 



Method of Cementing Cells without Heat. — The thin glass, 

 the tubular, the drilled, and aU the other forms of cells pre- 

 sently to be described, may be fastened to a bottom glass 

 or slide by means of one or other of the following cements, 

 viz., a mixture of gold-size and lamp black, or gold-size and 

 litharge or red-lead, or a solution of asphaltum in turpentine j 

 in aU these cases, the parts of the cell that are to be cemented 

 must be simply painted over with a tolerably thick layer of 

 one of the above cements, and then be laid on the slide, and 

 be put aside until the cement is suflSciently hard for the cell 

 to be used, which wiU often require many days. 



Cementing Cells by Heat. — The most efficacious plan, how- 

 ever, is to employ one of two substances known in commerce 

 as Canada balsam or marine-glue, both of which must be 

 liquefied by heat, and, to effect this, a simple apparatus, such 

 as a small plate of sheet-iron, supported in some way or other 

 over a lamp, must be provided. The size of the iron-plate 

 should be large enough to hold slides three inches long by 

 one wide ; it can be supported in various ways ; if the plate be 



