82 



TtiE MICROSCOPE. 



June, 



Bicarbonate of soda, [common baking soda], when dis- 

 solved in cold water and allowed to dry slowly forms 

 crystals like those shown in fig. 1 5 and t. If dried by 

 holding the slide over a lamp, the crystals are imperfect 

 and much like the center of fig. 1 s. 



To prepare a slide of sugar crystals dissolve a little 

 sugar in water to form a thick syrup, spread it on a 

 cover-glass and dry quickly over a spirit lamp. When 

 dried put in a damp place for twenty-four hours, or 

 more, when crystallization will have taken place. The 



crystals should always be formed on the cover-glass 

 when one wishes to make a permanent mount and every 

 trace of grease must be removed by cleaning with liquid 

 potassse or ammonia immediately before using. Always 

 very great care must be taken that none of the agent be 

 left upon the cover-glass, as it may interrupt and change 

 the shape or position of the crystals or even alter their 

 form. The same crystals may present many different 

 forms according to the conditions under which they are 



