"By the kind permission of our Warden, Mr. Mackenzie, I now forward you copy of correspondence relative to one of the resources of this colony, which I think worthy of a niche in your columns, especially as it is well worth the serious attention of home capitalists, as offering a very safe and large field for their capital.
"I may premise, we have the same 'substance' referred to in the following letter in abundance here at Mount Blackwood: —
November 10, 1855.
" 'Sir,—I have the honour to inform you, that according to your request, I have examined the rocks from the Maryborough Gold Fields, returned herewith.
" 'They consist of bluish-black shales, with thin veins of alumina and silica, mixed with iron pyrites.
" 'This rock belongs to the primary stratified series, and is found at McIvor, Cheswick's Creek, and near Melbourne.
" 'In England and in America this shale is quarried for the purpose of procuring alum. By the decomposition of iron pyrites, in connexion with a slate of shale, a new set of chemical products results — sulphate of iron, that is, sulphuric acid, and oxyde of iron. The sulphuric acid unites with the
