COMPOUNDS DEPOSITED BY ASCENDING SOLUTIONS. 1089 



tant amounts by ascending water at the first concentration are silver, gold, 

 and copper. Metallic gold, copper, and silver are also produced in connec- 

 tion with the reactions of descending water, but such deposits are not here 

 considered. Their development is treated on pages 1158-1174. All of 

 the metals mentioned, with the exception "of g*old, occur in the form of 

 sulphides. The sulphides are either simple binary salts or are ternary 

 salts, such as sulpharsenites, sulpharsenates, sulphantimonites, and sulph- 

 antimonates. The sulpharsenical and sulphantimonical compounds will 

 not be considered separately from the simple sulphides. The important 

 tellurides are those of silver and gold. An important oxide deposited by 

 ascending water is magnetite, and possibly franklinite and zincite belong 

 here. Of the carbonates that of iron is of the greatest consequence. Of 

 the silicates that of zinc may belong here. Of course many other oxides, 

 carbonates, and silicates are found in ore bodies; but so far as these are 

 in sufficient abundance to constitute workable ore deposits, it is believed, 

 as will be fully explained later, that these compounds do not belong to the 

 class of ores deposited by ascending water. 



Why compounds deposited by ascending- waters are, for the most part, 

 not oxidized compounds, but metallic compounds, sulphides or tellurides, 

 is easily explained. The widely disseminated, downward-moving water, 

 bearing oxygen, is robbed of this constituent early in its course. Ferrous 

 compounds are abundantly present in the rocks in the forms of magnetite 

 and silicates. Iron is a strong base; and where ferrous compounds are 

 present they continue to abstract the oxygen of the downward-moving 

 waters until it has practically disappeared. Moreover, buried organic 

 matter takes oxygen from underground waters. Hence oxidizing com- 

 pounds do not exist in the deep-seated ascending' water. 



solution. — It has been stated that gold is deposited by ascending waters 

 in important amounts. The maimer in which gold is dissolved and trans- 

 ported to ihe greatest extent in underground solutions is not well known. 

 As a matter of experiment it has been long- known that gold is soluble in 

 ferric chloride and in cupric chloride. Doelter has shown that gold is some- 

 what readily soluble in a 10 per cent solution of sodic carbonate, and also 

 mon xlvii — 0i 69 



