1106 A TREATISE ON METAMOKPHISM. 



SOLUTION OF SULPHIDES. 



It is well known that the sulphides of copper, mercury, iron, nickel, 

 lead, zinc, arsenic, and antimony are soluble in alkaline sulphides. Illus- 

 trating this general statement, Becker" has shown experimentally that the 

 natural sulphide of mercury, cinnabar, the natural sulphide of iron, pyrite, 

 the sulphide of copper, and the sulphide of zinc are soluble in sodic sul- 

 phide. Along the same line as Becker's work Doelter has shown that 

 pyrite, stibnite, sphalerite, arsenopyrite, chalcopyryite, bournonite, and 

 galena are all soluble in sodic sulphide." 



Becker has further shown that the sulphides of iron, copper, zinc, , 

 arsenic, and antimony are also soluble in alkaline carbonates containing, 

 but not saturated with, hydrosulphuric acid. c This is partly equivalent to 

 saving that they are soluble in sodium sulphide; for if hydrogen sulphide be 

 introduced in sodium-carbonate solution, the following reaction immediately 

 takes place: 



Na 2 C0 3 +H 2 S=Na 2 S+H 2 0+C0 2 



But the observation by Becker is important, since it gives a method by 

 which sodium sulphide, a solvent for the sulphides of the heavy metals, 

 may be produced. In this connection it should be recalled that the 

 carbonates of the alkalies are among- the most abundant compounds 

 carried by underground solutions, and hydrog'en sulphide is known to be 

 very common in such solutions. Therefore it is certain that considerable 

 quantities of sodium sulphide will be produced where these two classes of 

 solutions come together, as they are often sure to do. The formation of 

 sodium sulphide in consequence of the mixture of sodium carbonate and 

 hydrogen sulphide is probabty of great importance in the genesis of ores. 

 Confirming the conclusions of Becker and Doelter, observation has 

 shown that at Steamboat Springs, Nevada, and Sulphur Bank, California, 

 mercuric sulphide and iron sulphide are transported in solutions containing 

 sodic sulphide, hydrogen sulphide, sodium carbonate, and carbon dioxide. 



a Becker, G. F., Quicksilver deposits of the Pacific coast: Mon. U. S. Geol. Survey, vol. 13, 

 1888, pp. 428-435. 



6 Doelter, C, Einige Versuche fiber die Loslichkeit der Miueralien: Tschermaks Mineral. 

 Mittheil., Bd. XI, 1890, pp. 323-324. 



o Becker, cit, pp. 432-435. 



