MERCURY. 179 



of melted silver. When submitted to a sufficient degree of 

 cold, it is similar in appearance to other metals, and may be 

 beaten into plates. At the poles it would probably be al- 

 ways solid. It readily combines with several of the other 

 metals, and forms with them what are called amalgams. 

 Mercury is used in large quantities for separating gold and 

 silver from their ores ; for silvering mirrors, for water-gilding, 

 for making barometers and thermometers ; by the philoso- 

 phical chemist for many purposes of the laboratory ; and in 

 the manufactory of vermilion. It has also various and 

 important uses in medicine. By dissolving mercury in 

 nitric acid, a fulminating powder is obtained, two or three 

 grains of which, laid on an anvil and struck smartly with a 

 hammer, will explode with a loud report. Four grains will 

 occasion indentation in the hammer and anvil. By exposing 

 mercury to cold of a proper degree of intensity, which may 

 be easily accomplished by certain freezing mixtures, it be- 

 comes a solid metal. If a lump of this be dropped into a 

 cup of warm water, the solid metal will immediately become 

 fluid, and the fluid water in the same instant will become 

 solid. If a glass be used for the experiment, it should be 

 infolded within a cloth to prevent accidents ; for sometimes 

 it will be shivered in pieces by the rapidity ©f the action. 



The quicksilver mine of Guanca Velica, in Peru, is 170 

 fathoms in circumference, and 480 deep. In this profound 

 abyss are seen streets, squares, and a chapel. Thousands of 

 flambeaux are continually burning to enlighten it. The 

 mine generally affects those who work in it with convul- 

 sions. Notwithstanding this, the unfortunate victims of an 

 insatiable avarice are crowded together, and plunged naked 

 into these abysses. Tyranny has invented this refinement 

 in cruelty, to render it impossible for any thing to escape its 

 restless vigilance : — 



For in the dark Peruvian mine confined, 



Lost to the cheerful commerce of mankind, 



The groaning captive wastes his life away, 



For ever exiled from the realms of day ; 



While all forlorn and sad, he pines in vain 



For scenes he never shall possess again. Falconer. 



Questions. — 1. What is silver.? 2. In what states is it found? 

 3. For what used ? 4. How can you ascertain its purity ? 5. What is 

 said of nitrate of silver ? C. Of silvering ? 7. Plating ? 8. Describe 



