124 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VOL. II. 



426° C. become fluid. Under normal conditions these rocks require 

 from 1371° C. to 1649° C. to liquefy them. If any alkali were present 

 the figures would be considerably reduced. This is termed hydrothermal 

 fusion. 



Further, by fusing lead and sulphur together we can make artificial 

 galena, the same is true of silver. We also are able to form silicate as 

 well as sulphide of gold in our laboratories. That silicate of gold exists 

 in nature I was first led to believe by finding that metal in quartz, which, 

 before treatment, had not the least appearance of containing it, and I 

 subsequently found that my results justified me in believing that I was 

 right in my conclusions, and last but not least, as I have before men- 

 tioned, that galena veins are very rich in one stratum, but on entering 

 another, provided it has a different composition, they become very poor, 

 thus sustaining my theory that the entire vein matter was originally 

 incorporated in that stratum of rock which forms the wall rock of that 

 part of the strata which has the greatest body of metal. 



Again, the gold may have been reduced by erosion to small grains 

 and in time become disseminated through the debris of its disintegrated 

 matrix, thus forming stream gold of which we have examples in our 

 placer mines of California, Australia, Siberia, and other places. Now, 

 were ferrous or ferric sulphate, Fe. SO^ and Fe^,, 3 SO^, to percolate 

 through this gravel they would certainly dissolve a large portion of the 

 gold, thus preparing a solution for the formation of auriferous iron 

 pyrites. For the origin of the ferrous and ferric sulphates we have iron 

 pyrites, which is ferric sulphide Fe. So, which would lose half its sulphur 

 at a white heat forming ferrous sulphide Fe. S ; this, when heated in 

 air would form the sulphide, or else these changes might be brought 

 about by atmospheric agency, as I have mentioned in a foregoing part of 

 this paper. 



We will now consider those deposits of galena which occur in non- 

 metamorphic rocks, which are principally in limestone, a good illustra- 

 tion of which are the lead regions of Missouri and Wisconsin, which are 

 not, properly speaking, veins, but have been formed by surface solutions 

 containing the galena and accompanying minerals, namely, calcspar, 

 baryta and chert in solution. The solution was probably an alkaline 

 carbonate or sulphide, as these are the natural solvents of the foregoing 

 minerals. As I befoi^e said, these deposits are not to be compared 

 to those which occur in the older metamorphic rocks as regards the 

 amount of silver or gold they contain, but are invaluable as lead 

 producing deposits. 



Taking it for granted that the principal body of metal was buried 



