LIGHT. 



accompanying development of polarization properties 

 may be projected. It will be simply necessary to mag- 

 nify the object by using a lens of short focus as in the 

 former instruction for the solar microscope. The strip 

 of clear glass, holding a drop of a saturated solution 

 of the substance, the objective, and the Nicol's prism 

 being put near the focus of a condenser of twelve to 

 eighteen inches focus, that the specimen may be lighted 

 as much as possible, and also have sufficient light trans- 

 mitted. 



Fig. 1OO. 



The following list of salts and other substances will 

 be found to be beautiful objects for polarized light : 



Alum, 

 Borax, 



Carbonate of Lime, 

 Carbonate of Soda, 

 Chloride of Barium, 

 " " Copper and 



Ammonia, 



Chloride of Sodium, 

 Chlorate of Potash, 

 Citric Acid, 

 Nitrate of Bismuth, 



" Copper, 



" Potash, 



Oxalate of Ammonia, 

 " " Lime, 



Oxalic Acid, 



Picric Acid, 



Prussiate of Potash, 



Salicine, 



Sulphate of Copper, 

 < 



Magnesia, 

 Sulphate of Iron, 

 " " Soda, 

 " Zinc, 

 Sugar, 



and 



