MERCURY, SILVER, GOLD, AND PLATINUM. 205 



though not as rapidly, at ordinary temperatures. This you 

 can prove by a simple experiment. Put some mercury in 

 a phial, and fasten to the cork a little bit of wood having 

 some gold-leaf attached to it. The gold, after a few days, 

 will have a white color, because the mercury has risen in 

 vapor and united with the gold, forming an amalgam. 

 There are two oxides of mercury, one of which, called red 

 precipitate, is with its bright red color a striking example 

 of the great difference which is so often seen between the 

 properties of a compound and those of its constituents. 

 Mercury is sometimes found native. It is said that the 

 mines of Mexico were discovered by a hunter, who, as he 

 took hold of a shrub in climbing a mountain, tore it up by 

 the roots, and a stream of what he supposed to be liquid 

 silver burst forth. But the metal is commonly obtained 

 from the ore called cinnabar, a sulphide. 



So readily does the mercury in cinnabar part with the 

 sulphur that merely roasting it in a current of heated air 

 answers to reduce it. Sulphurous anhydride is formed by 

 the union of the sulphur with the oxygen of the air, and 

 this gas passes together with the vapor of the mercury into 

 a cool chamber, where the liquid mercury collects by the 

 condensation of the vapor. 



375. Vermilion. Cinnabar is of a beautiful red color, but 

 precipitated mercuric sulphide is black. If this artificial 

 sulphide is sublimed, then, without any chemical change, it 

 becomes a brilliant red, and is the so-called vermilion. This 

 substance is sometimes adulterated with minium or red- 

 lead, but the fraud can be easily detected. If a little of 

 pure vermilion be thrown upon a live coal, it is entirely 

 volatilized or sublimed with a blue sulphurous flame ; but 

 if it be adulterated with minium it will not all volatilize, 

 and beads of metallic lead will remain on the coal. 



376. Chlorides of Mercury. Mercurous chloride, Hg 2 Cl 2 , 



M 



