3o8 AQUATIC MICROSCOPY FOR BEGINNERS. 



Gallic Acid. — A small drop of a .strong solution in al- 

 cohol should be allowed to evaporate very slowly, 



Pyrogallic Acid. — A strong cold solution in water 

 forms long needle-shaped crystals, "but if a very 

 minute shower of some insoluble foreign substance be 

 allowed to fall upon the solution when on the slide the 

 effect is grand — each minute speck forming a nucleus 

 around which the needle-shaped crystals gather, form- 

 ing, if examined with a selenite slide, so resplendent 

 an object that no words of mine can adequately des- 

 cribe it." 



Chlorate of Potash. — Make a strong solution in hot 

 water and allow a small drop to spread evenly over the 

 cell and evaporate slowly. To form dendritic, or tree- 

 like crystals of this salt, heat a drop over the lamp. 

 As soon as the crystals begin to form at any point, tilt 

 the slide so that the liquor may run off, then continue 

 the crystallization by gentle warmth. 



There are many other salts which produce beautiful 

 crystals when treated in the. foregoing or in a similar 

 manner, but the student would doubtless prefer to ex- 

 periment for himself, rathe'r than to have a bare list 

 set down before him. And there are innumerable 

 other common objects easily to be procured and worthy, 

 of study. It is not possible to enumerate a millionth 

 part of them. Examine for yourself. Try and see 

 what a good thing a microscope is. And the writer 

 wishes the reader every success in the use of the de- 

 ilightful instrument. 



