Br. Carl Ochaenim — On Metalliferous Deposits. 317 



chlorine and bromine. The salt sohitions which changed the 

 character of the veins in this case therefore were not subterranean 

 before they reached the deposited metals. 



• The expression " alhaline " which Le Conte has already used before 

 in his "Elements of Geology" (1879), when treating of the forma- 

 tion of metalliferous ores, should also give place to the word saline ; 

 for chloride of magnesium, which certainly plays a very important 

 part in the dissolving process of metallic substances, belongs just as 

 little to the alkalies as does sulphate of magnesia, which is another 

 large constituent of mother liquors. It is well known that many 

 metallic sulphides crystallize out of mother liquor salts, evidenced by 

 the finding of masses of crystallized pyrites in kieserite and galena 

 in anhydrite. Silicates are also formed from solutions of mother 

 liquor (quartz-crystals in carnallite ; tourmaline in anhydrite changed 

 into gypsum). The proof that gold is contained in many cases 

 in American silver ores in the form of chloride, has been already 

 demonstrated.^ 



That mother liquor has been an agent in the formation of Sulphur 

 Banks and Steamboat Springs is very clear ; the presence of borium 

 in them is of itself a sufficient evidence of that. 



The view of Gr. Bischof that uprising waters are stopped in their 

 progress by their own depositions can only be partially correct. 

 The same chemist says that deliquescent chlorides (chloride of cal- 

 cium and chloride of magnesium) never occur in a solid state, not- 

 withstanding that the latter (named by me Bischofit) occurs in 

 massive bulk at Leopolds-hall, near Strassfurt. 



Haidinger has already advanced the view that the changes of 

 many calcareous formations into dolomite must have been produced 

 through the agency of sulphate of magnesia, although it was not 

 then known how such large quantities of the solutions of magnesium- 

 salts originated,. and this problem was not solved until my views 

 on the subject were brought forward. 



The foregoing answers a very important question, which might be 

 put to Professor Le Conte as to the source of the alkaline solutions, to 

 which he attributes the formation of metalliferous veins. My long- 

 investigations in various parts of the world enable me to answer this 

 question incontrovertibly, and beyond this they enable me to desig- 

 nate mother liquor as one of the most influential of geological agents. 

 I must remark here, however, that the opinion that adjacent rocks 

 furnished materials for metalliferous veins has already been ex- 

 pressed by Forchhammer (1847), and consequently that Sandberger, 

 against whose views Le Conte's expressions were partially directed, 

 does not stand alone in that opinion. 



If saline solutions, or let me say mother liquors, do not come into 

 contact with metallic substances on their flow from higher levels ; 

 then salt springs, but not metalliferous beds, are formed. 



Now as to the concluding words of Le Conte's sentence, " Sub- 

 terranean waters of any kind, but especially alkaline, at any tem- 

 perature, but mostly hot, circulating in any direction, but mainly 

 1 Zeitsclirift, etc., vol. xxxiv. p. 519. 



