POLARIZED LIGHT. Ill 



Succinic acid. 



Stearine. 



Picrate of Aniline. 



Chlorate of Cinchoniiie. 



Borate of Soda. 



Margarine. 



Quinidine. 



Santonine. 



Sugar. 



Uric acid. 



Chromate of Potash. 



Paraffine. 



Platino-cyanide of Magnesium. 



The beginner need not make use of a large 

 quantity of the material he is about to experiment 

 with, and the only apparatus he requires is a small 

 test-tube about 4 inches long and half an inch in 

 diameter. Fill about 1 inch of this with distilled 

 water (if the crystals are soluble in water), add 

 two or three crystals, and dissolve with heat if 

 necessary ; take up a small quantity with a dip- 

 ping tube and drop it on a perfectly clean slide or 

 cover. It is as well to prepare several slides, 

 allowing some to dry slowly, and others to be 

 evaporated over a spirit-lamp. 



One of the most beautiful examples of crystalli- 

 zation is that of Salicine,and as merely recrystallizing 

 it from its solution will only result in disappoint- 

 ment, we will give explicit directions for the pro- 

 duction of the rosette form of crystals as in Fig. 2, 

 plate 9. A saturated solution of the alkaloid must 

 be prepared, a drop of the solution placed on a 

 glass cover, and held over a spirit-lamp until it 

 not only evaporates the water, but melts the re- 

 siduum. The cover must now be put in a cool 

 place, and protected from dust. If the cover is 



