260 METALS. 



extreme cold. Nitric acid is its proper solvent. Mer- 

 cury is sometimes found in the metallic form, but more 

 commonly as the sulphuret or cinnabar, which is its 

 principal ore. It is said that the mines in Mexico were 

 accidentally discovered by a native hunting among the 

 mountains. Laying hold of a shrub to assist him in 

 his ascent, he tore it up by the roots, and a stream of 

 what he supposed to be liquid silver flowed from the 

 broken ground. 



How is mer- 650. PRODUCTION. Mercury is prepared 

 cury obtained ? f rom t h e sulphuret, by simple roasting in a 

 current of heated air. This metal yields its sulphur so 

 readily to the oxygen of the air that no other agent is 

 essential in its production. The mercurial vapors pass 

 along with the gas, into tubes or chambers where the 

 temperature is lower, and are there condensed to the 

 liquid form. 



Mention other 651. Mercury may also be produced from 

 methods. fa e sulphuret by the employment of iron 



filings to remove the sulphur, as in the case of lead. 

 Burned lime may also be used. Its calcium combines 

 with the sulphur and uses its own oxygen for the 

 partial conversion of the sulphuret thus formed into 

 sulphate of lime. 



652. ACTION OF HEAT AND AIR. Mercury, 



What is the J7 



action of heat like water, may be boiled away and con- 

 verted into vapor, by the application of 

 heat. At 39 below zero it freezes. It is 

 always to be borne in mind in experiments with this 

 metal arid its compounds, that its fumes as well as its 

 salts, are extremely poisonous. By free access of air and 



