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balsam covering the object. The slide being now held by the nip- 

 pers at one end, in rather an inclined position upwards, place the 

 other end over the centre of the chimney of the lamp, so that 

 the extreme end of the glass may first receive the heat, which 

 will thus gradually extend towards the object. The proof of 

 its having done so, efficiently and sufficiently, will be that the 

 balsam will have flowed (for that moiety at least nearest towards 

 the heat) to the extreme edge of the thin glass, carrying out with 

 the surplus all air-bubbles. The heated end of the slide is now to 

 be placed in the nippers, and the reverse end of the glass is to be 

 subjected to the same process, when the like result will be exhibited. 

 The slide is then to be immediately withdrawn from the flame, and 

 should be suffered to remain in a horizontal position till nearly cool, 

 when a small piece of wood, rather pointed, should be pressed, per- 

 pendicularly, upon the centre of the upper or thin glass ; this will 

 expel all superfluous balsam, and with it any extraneous matter. 

 Should it happen, after the above process, that any air-bubbles should 

 be generated by the object, which sometimes happens, the slide should 

 be put aside for a day or two, when they will all disappear. If 

 the balsam require hardening, place the slide for two or more 

 days upon the mantel-piece, the gentle heat of which will be 

 sufficient for that purpose. 



Should this simple detail be found useful to any of the microscopic 

 fraternity of which I am so humble a member, it will afford me the 

 greatest pleasure. 



