CHEMISTBY AND THE MICROSCOPE 



a liquid in which the maximum amount of solid 

 is dissolved. 



We have already described the most simple way 

 in which crystals may be formed, and we may easily 

 make objects for our microscope in this manner of 

 all the substances we can find which are soluble in 

 water. With some we shall find that crystals do 

 not form easily, in which event we may modify our 

 tactics and warm one drop of saturated solution on 

 the slide till nearly all the moisture is driven off, 

 then there should be no difficulty in watching the 

 crystals in process of formation. Common salt, 

 sugar, alum, borax, washing soda, iron sulphate, 

 called also green vitriol and copper sulphate, or blue 

 vitriol, are common and easily obtained substances, 

 all soluble in water. As we carry our experiments 

 a little further we shall find that crystals formed 

 from cold solutions as suggested in our first method 

 differ from those formed from hot solutions. Again, 

 if we use some other substance than water as our 

 solvent the crystals which separate out will differ 

 once more. Many very interesting experiments may 

 be tried on these lines. 



Many beautiful crystals may be obtained by dis- 

 solving various substances in gelatine or gum. The 

 method is simple. Gently warm a little gelatine, 

 to which is added an equal volume of water, in a 

 chemist's test-tube. When the gelatine has all dis- 

 solved make a saturated solution of the substance, 

 from which crystals are derived. Green or blue vitriol 

 are good subjects for the experiment. Add a little of 



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