CONTENTS Page Introdctory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Historical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Theoretical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 I . Chloridation or Sulphatation . . . . . . . . . . . . . . . . . . . . . 14 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Electrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 . 2 I I . Persulphatation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Historical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 6 Theoretical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1 On Two New Electrochemical Processes for the Extraction of Silver and Gold from Their Ores INTRODUCTORY Some two years ago, Mr. Gilbcrt Gurney, a practical miiiing man, came to this Vniversity with some of the non. wellknown Tonopah gold aid silver ores, with a view to fincling o twh at could be done wit11 thein in tlle line of a retnuncrative treatment of tlie same. As Mr. Gurney, upoil the ivritcr coming to know him, admitted frankly to have very li nitetl cotnmand of tile knowledge of chenlistry or metallurgy necessary to c-pe with tlie problem it1 question, the latter, by conlmnn consent, soon tlevolved LIpon the present writer, while Mr. Gurney himself liil dly offered to purvey certain facilities vhereby the ncccssary investigations were to be carried out. The following is an account of the results of tlte various experiinents and studies that were undertaken in this line cluring the acadei lic year 03- 04, ant1 continuetl tl roughout the year 04- 05. It is necessary to state here that nearly all the assays inacle in connectiol with the first part Cliloridation n ethocl of this study were made by Thomas Price Sr Sons, professional assayers of San Francisco, through the courtesy of hlr. Gurney. On the other hand, the writer assumes responsibility for the remaining assays, all of which were made at tlie chemical laboratories of this University. HISTORl CAL It seems to be an admitted fact in mining circles that, in spite of the goodly number of the various methods proposed, some in jourilal and mostly in patent literature, in the last half century or so, the desideratuni of an economic, wet process for the simultaneous extraction of the precious metals gold and silver froni their sulphide ores is still keenly felt. 111-deed, the 111ethods in vogue, even at present, are still some one form or another of smelting, amalgamation, Augustin, or hypo-sulphite processes, all of which entail, at some point or other in the course of their operations, certain costly treatments, now in the for111 of a prelii linary roasting, and now in form of constant consumption or rejection of . the reacting chemicals, such as salt, copper sulphate, and mercury or its salts, while all, except smelting, are none too efficient, even irrespective of the cost of treatment. Although at the time the writer begail the studies which form ...