Up to a comparatively recent time it was considered heretical for any one to advance the theory that gold had been deposited where found by any other agency than that of fire.  As late as 1860 Mr. Henry Rosales convinced himself, and apparently the Victorian Government also, that quartz veins with their enclosed metal had been ejected from the interior of the earth in a molten state.  His essay, which is very ingenious and cleverly written, obtained a prize which the Government had offered, but probably Mr. Rosales himself would not adduce the same arguments in support of the volcanic or igneous theory to-day.  His phraseology is very technical; so much so that the ordinary inquirer will find it somewhat difficult to follow his reasoning or understand his arguments, which have apparently been founded only on the occurrence of gold in some of the earlier discovered quartz lodes, and the conclusions at which he arrived are not borne out by later experience.  He says:—­“While, however, there are not apparent signs of mechanical disturbances, during the long period that elapsed from the cooling of the earth’s surface to the deposition of the Silurian and Cambrian systems, it is to be presumed that the internal igneous activity of the earth’s crust was in full force, so that on the inner side of it, in obedience to the laws of specific gravity, chemical attraction, and centrifugal force, a great segregation of silica in a molten state took place.  This molten silica continually accumulating, spreading, and pressing against the horizontal Cambro-Silurian beds during a long period at length forced its way through the superincumbent strata in all directions; and it is abundantly evident, under the conditions of this force and the resistance offered to its action, that the line it would and must choose would be along any continuous and slightly inclined diagonal, at times crossing the strata of the schists, though generally preferring to develop itself and egress between the cleavage planes and dividing seams of the different schistose beds.”

He goes on to say, “Another argument to the same end (i.e., the igneous origin) may be shown from the fact that the auriferous quartz lodes have exercised a manifest metamorphic action on the adjacent walls or casing; they have done so partly in a mineralogical sense, but generally there has been a metamorphic alteration of the rock.”  Mr. Rosales then tells his readers, what we all know must be the case, that the gold would be volatilised by the heat, as would be also the other metals, which he says, were in the form of arseniurets and sulphurets; but he fails to explain how the sublimated metals afterwards reassumed their metallic form.  Seeing that, in most cases, they would be hermetically enclosed in molten and quickly solidifying silica they could not be acted on to any great extent by aqueous agency.  Neither does Mr. Rosales’s theory account at all for auriferous lodes; which below water level are composed of a solid mass of sulphide of iron with traces of other sulphides, gold, calcspar, and a comparatively small percentage of silica.  Nor will it satisfactorily explain the auriferous antimonial silica veins of the New England district, New South Wales, in which quantities of angular and unaltered fragments of slate from the enclosing rocks are found imbedded in the quartz.