METALS. 



201 



by the application of heat ; some of them at quite a moder- 

 ate temperature. Thus mercury, arsenic, and zinc are vol- 

 atile below a red heat. Indeed, at ordinary temperatures 

 mercury is somewhat volatile, and there is always a thin 

 vapor of this metal in the vacuum of the thermometer, so 

 that it is not strictly a vacuum. 



TABLE SHOWING THE FUSING POINTS OP METALS. 



F. 



C. 



Mercury. 39 39.4 



Rubidium 101.3 38.5 



Potassium 144.5 62.5 



Sodium 207.7 97.6 



Lithium 356 180 



Fusible Tin 442 235 



below a - Bismuth 497 258 



red heat. Thallium 561 294 



Cadmium 599 315 



Lead 626 330 



Arsenic. Unknown. 



Zinc 773 412 



Antimony 842 450 



fSilver. 1873 1023 



Copper 1996 1091 



Infusible Gold 2016 1102 



22T*"; * 2786 153 



red heat. 



Manganese, f Hi hest heat 

 .Palladium, J 

 Chromium, 

 Titanium, 



Osmium, [ Infusible in ordinary blast-furnaces. 

 Iridium, 

 Platinum, 



277. Welding. Some of the metals, as they approach to 

 the melting point, become semi-fluid or pasty. This is the 

 case with iron. In this state it can be welded that is, two 

 pieces of it can be made to unite by hammering them to- 



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