[319] , SCIENTIFIC MANUAL. 33 



Litharge and red lead are two different oxides of lead. 

 The latter is used chiefly in glass making. 



Sugar of lead is its combination with acetic acid. White 

 lead is the carbonate, manufactured largely for use in paints. 



Mercury, known as quicksilver, is a heavy liquid which 

 is not often found except in combination with sulphur. It 

 freezes at 40 degrees below zero. It is used largely in va- 

 rious meteorlogical instruments, in extracting gold and 

 silver from their ores, and for silvering mirrors. An Amal- 

 gam is a union of mercury with other metals. In medi- 

 cine, mercury is contained in "blue mass," in the me- 

 tallic form very finely disseminated through the mass ; in 

 combination with chlorine, as calomel and corrosive sub 

 limate. 



Manganese is one of the elements found in all soils, 

 though generally in very small quantities. It is largely 

 used in various manufactures. 



Nickel occurs combined with other elements. Its chief 

 use is in the alloys of German silver. 



Platinum is a comparatively rare and valuable metal, used 

 principally in chemical laboratories. It can only be melted 

 at the very highest heat, viz : that produced by burning 

 oxygen and hydrogen together. 



Silver is found both pure and combined with other min- 

 erals. It is used principally in alloys with copper, as in 

 coins and articles of plate. Its most important salt is 

 the nitrate of silver, known as lunar caustic when in sticks. 



Indelible Ink, for marking linen, is made of this salt. 



Tin has been found in but few localities, always com- 

 bined with another element. It is used largely in the arts 

 for covering iron plates. 



The "sheets of tin," of which ordinary tin vessels are 

 made, are only thin sheets of iron covered with a coating 

 of tin to protect them from rusting. 

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