CHEMISTRY AND THE MICROSCOPE 



detection can solve mysteries which would have 

 baffled all the scientists in the world in days gone 

 by. 



Our chemical studies with the microscope may 

 well begin with various common crystals; they are 

 usually easy to prepare; the process of crystalliza- 

 tion is always interesting to watch, and as objects 

 for the microscope it would be difficult to find any- 

 thing more beautiful than these home-made gems. 

 All crystals should be examined by reflected as well 

 as by transmitted light. When we are working 

 with the former lighting, a piece of black paper 

 beneath the slide will help to show up the objects 

 to better advantage. 



The easiest method of obtaining crystals of any 

 substance which is soluble in water is to make a 

 saturated solution in this liquid, to put a small 

 drop upon a slide, then to tilt the microscope 

 slightly so that there is a thin film of solution at the 

 upper side of the drop. The microscope must not 

 be tilted so much that the liquid runs from the slide 

 on to the stage. Where the film of liquid is thin 

 crystals will be found first. A word of explanation 

 is necessary concerning the term saturated solution, 

 especially as we may have occasion to use it many 

 times. When we add a solid to a liquid in which 

 it is soluble, we shall find that the Hquid 

 will take up a certain amount of the solid 

 and no more; when, on the addition of more 

 solid it fails to dissolve, we have reached the 

 saturation point. A saturated solution then is 



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