45 



balsam covering the object. The slide being now held by the nippers 

 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, effi- 

 ciently 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 withdrawn from the flame, and should be suffered to remain in a hori- 

 zontal position till nearly cool, when a small piece of wood, rather 

 pointed, should be pressed, perpendicularly, 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 some- 

 times 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. 



TRANS. MIC. SOC. VOL. II. 



