70 HOW TO USE THE MICROSCOPE 



Deeper cells are conveniently made with vulcanite 

 rings supplied at small cost by the dealers ; or with 

 rings of paper dipped in melted paraffin wax and 

 allowed to dry. These rings are attached to the 

 centre of the glass slip with a layer of gold-size ; 

 they must stick firmly and be in perfect contact 

 with the glass. 



Slips and cover-glasses must be thoroughly clean. 

 The former should be washed in soap and water, 

 and dried with a piece of soft linen ; the latter are 

 very fragile, and require careful handling ; they, 

 too, should be washed and dried, and then receive 

 a final polish with chamois leather. With a little 

 practice the worker will be able to handle them 

 without breakage. 



Some opaque objects require securing in position 

 in their cells with a tmy drop of gum. This, of 

 course, is placed where it will not interfere with 

 observation of the object, and must be thoroughly 

 dry before the cover -glass is affixed. Wing scales of 

 lepidoptera and pollen grains from flowers are 

 commonly secured by a film of thin gum on the cell 

 bottom. The gum is laid on the glass, and allowed 

 to dry ; then it is made sufficiently moist by breath- 

 ing upon it. The objects are placed on the film, 

 and when all is thoroughly dry the cell is covered 

 and sealed. Or the film of gum may be laid on 

 the cover-glass and the objects secured on it instead 

 of the bottom of the cell. Many objects are secured 

 without adhesive material : placed in a shallow cell, 

 the pressure of the cover glass is sufficient to keep 

 them from moving. 



It used to be the custom to mount opaque objects 



