130 ECONOMIC GEOLOGY 



vapor by heat. The calomel condenses in the cooling chambers 

 as a white sublimate. 



Uses of Mercury. The most important use of mercury is to 

 form amalgams. Most metals amalgamate with mercury. 

 Sodium and potassium amalgams are used in organic analysis. 

 Tin amalgams are used in ordinary mirrors, gold and silver 

 amalgams in filling teeth. A common amalgam for this purpose 

 consists of silver, copper and tin with enough mercury to amal- 

 gamate the mixture. Copper and zinc likewise amalgamate 

 with mercury. The largest single use lies in the extraction of 

 the precious metals from their various ores. Mercury is used 

 in thermometers but these are not accurate at temperatures 

 exceeding 30 below zero. Mercury is used also in the arts, as 

 in the electrolytic process for the manufacture of sodium and 

 chlorine. The metal is unattacked by a large number of gases, 

 therefore it is used in collecting and measuring gases which are 

 soluble in water. Mercury compounds are used in medicine 

 of which calomel is the most important. The bichloride of 

 mercury, known as corrosive sublimate, is used in mercurial 

 ointment and as an antiseptic for dog bites and snake stings. 

 The sulphide is used as a pigment under the name of vermilion. 



The unit of measure for mercury is different from that of the 

 other useful metals. The liquid metal is put up in flasks. Each 

 flask contains 75 Ib. The value of the metal is determined 

 by the market at San Francisco. An average quotation is about 

 $45 per flask. The output of mercury in the United States in 

 1910 was 1,612,500 Ib. 



There are two conditions that oppose a large production of 

 the metal. One is that many of the cinnabar deposits are 

 situated far from transportation and fuel. The other is that 

 small capital is not likely to be attracted to such localities. 



