SUMMARY. 473 



Solution and precipitation of cinnabar and other ores. TllG WateVS of Steaillboat SprillgS 



are now depositing gold, pvoljably in the metallic state; sulphides of arsenic, 

 antimon}-, and mercury ; sulphides or sulphosalts of silver, lead, copper, 

 and zinc; iron oxide and possibly also iron sulphides; and manganese, nickel, 

 and cobalt compounds, with a variety of earthy minerals. The sulphides 

 which are most abundant in the deposits are found in solution in the water 

 itself, while the remaining metallic compounds occur in deposits from 

 springs now active or which have been active within a few years. These 

 springs are thus actually adding to the ore deposit of the locality, which 

 has been worked for quicksilver in former years and would again be ex- 

 ploited were the price of this metal to return to the figure at which it stood 

 a few years since. At Sulphur Bank ore deposition is still in progress. 

 The waters of the two localities are closely analogous. Both contain sodium 

 carbonate, sodium chloride, sulphur in one or more forms, and borax as 

 principal constituents, and both are extremely hot, those at Steamboat 

 Springs in some cases reaching the boiling-point. In attempting to deter- 

 mine in what forms the ores enumerated can be held in solution in such 

 waters, it is manifestly expedient to begin by studying the simplest possi- 

 ble solutions of the sulphides, and particularly of ciimabar. 



The statements in the previous literature of this subject are incomplete 

 and in part discordant, so that the subject required reinvestigation, particu- 

 larly as to the sodic solvents. It was found that, provided a small quantity 

 of sodic hydrate be present, one molecule of mercuric sulphide unites with 

 two molecules of sodic sulphide to form a freely soluble sulphosalt and that 

 an excess of sodic hydrate is without effect upon the solubility. Even when 

 sodic hydrate is entirely alisent, mercuric sulphide is freely soluble in aque- 

 ous solutions of sodic sulphide, though the contrary has repeatedly been 

 asserted; but either one molecule of mercuric sulphide then unites with 

 three of sodic sulphide, instead of two, or a mixture of sidphosalts nearly 

 corresponding to this compound is formed. 



Sodic sulphydrate wdien cold is absolutely without effect upon mercuric 

 sulphide, but when the mixture is heated on the water-bath the sulphydrate 

 is deconqiosed and sodic sulphide is formed; it unites with the mercuric sul- 

 phide in the proportion of four molecules of the former to one of the latter. 

 A perfectly limpid solution results. The same compound is produced when 



