CHTOICE AND USE OF APPARATUS 



little experience will teach how big a drop of Balsam 

 to use. 



Should we decide to use glycerine jelly, we take a 

 small globule of the jelly on one of our mounted 

 needles and place it in the centre of a clean slide. 

 Then we hold the slide a little above a lighted candle, 

 or even a match will do, to melt the jelly. Directly 

 it is melted the section is placed upon it, and we 

 proceed as before. Whichever mountant we have 

 used, the slides must be put away out of the dust, 

 and they must be fiat and not placed on edge. In 

 a few days the mountant will set, and we need take 

 no further precautions with the slides in which 

 Balsam was used, but those mounted in glycerine 

 jelly must be ringed, for the reason that glycerine 

 absorbs moisture from the air and gradually liquifies. 



The process of ringing is best performed upon a 

 turntable, which any dealer in microscope accessories 

 will supply. It consists of a circular brass plate 

 which revolves about its centre and to which the 

 slide to be ringed is affixed. A bottle of ringing 

 asphalt and a fine paint brush are essentials. With 

 a little of the asphalt upon our brush, we revolve 

 the turntable and place the brush against the edge 

 of the cover slip as it revolves, in such a manner that 

 we paint a narrow rim of asphalt over the junction 

 of cover slip and slide. The asphalt prevents mois- 

 ture from reaching the glycerine jelly. Of course we 

 may ring our slides without making use of a turn- 

 table, but it is not easy to paint a neat ring without 

 mechanical assistance. For square cover slips it is 



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