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merely, and not as bullion. This has been abundantly proved by the treatment of the Monowai and other Hauraki Gulf ores. The largest parcel treated at one time by the process was 22 cwt. in the company's vats in Dunedin. It was from the Mount Morgan Mine, in Queensland, and had been roasted at that mine before being sent to Dunedin. The ore contained 10 oz. 15 dwt. of gold per ton. The extraction was 95-6 per cent, of the gold, at a cost in chemicals (salt, sulphuric acid, and permanganate) of 4s. 4fd. per ton. The best extraction at the Mount Morgan works, where several trials were made, was 94f per cent., at an estimated cost, after roasting, of about 4s. 6d. per ton. The points that require most careful attention—repeated here for the purpose of emphasizing them —are : (1) Perfect dead calcination (with salt in the case of much copper or silver or both) ; (2) a perfectly clean pure quartz filter-bed ; (8) due attention to the proportion of the ingredients in making up the solution; and (4) seeing that the solution-tanks and leaching-vats are protected internally by a coating of paraffin-wax, as described above.

ELECTRO-DEPOSITION OF GOLD UPON THE GOLD OF OUE DEIFTS. [By William Skey, Analyst to the Department of Mines. Read before the Wellington Philosophical Society, 22nd December, 1897.] If among the many strange and fanciful theories that the ancient digger and the masterful miner have invented for the explanation of the various phenomena that they have observed in the solitudes of nature's laboratory there is one that as first presented to us appears the strangest—the farthest fetched of any of these—it is, I think, the one which maintains that the nuggets of our drifts have generally grown or been formed therein, and that even all gold can also grow therein— that is, in situ —and this by a kind of selective process, by which it accretes to itself the gold from its solution in the auriferous waters that flow around it—that, in fact, under favouring conditions every particle of gold acts as a nucleus for any soluble gold that it comes in contact with—that in reality gold as present in our spring waters has the same tendencies to go to gold in its uncoined state in the domain of nature as it has in its coined state in the hands of those who have it. Nor was this wild theory of the digger and the miner merely a speculative one, for they believed in it to such an extent that they acted up to it by purposely leaving gold—a little " seed-gold," as they termed it—in their tailings to draw the precious metal to itself for a profitable rewashing thereof. The first scientist, so far as I am aware, who had the hardihood to patronise this theory—to father it, I may say—was Dr. Selwyn, Secretary to the Mines Department, Victoria. This was in the sixties. His precise theory, as stated before the Eoyal Society of Victoria,* is thus given : " That nuggets may be formed, and particles of gold may increase in size, through the deposition of gold from the meteoric waters percolating the drifts, which water, during the time of our extensive basaltic eruptions, must have been of a thermal and probably of a highly saline character, favourable to their carrying gold in solution." Thus Dr. Selwyn; and though he did not furnish anything in its favour of a very convincing kind —nothing much more, in fact, than had already been adduced—he had performed the signal service of giving to this wild and unproven theory an air of respectability —the sanction of a great name : he had brought it to the forefront of science, and it was not long before converts to these views were made, one of whom, and the first, I believe, was Professor Ulrich, who gave much attention to the subject, and his remarks thereon appear in the work on the " Goldfields of Victoria," by Mr. E. Brough Smyth, F.G.S., pp. 356-57. In these he particularly draws attention to these three facts —(1) That nuggets even above 1 oz. in weight are of rare occurrence in quartz reefs; (2) that a tremendous cataclysmic force would be required to move large nuggets to the situation in the drifts that we find them in; and (3) that there is a great difference in the standard of fineness between alluvial and reef gold.! But whatever quantity of evidence had been adduced geologically for this accretion of gold on gold, one thing was lacking, for the theory had no solid ground to rest upon so long as the chemist did not, or could not, show some natural process by which was effected this building-up of gold on gold in the coherent reguline lustrous form that all nuggets and particles of native gold have taken. Years passed away, and no evidence of this kind was forthcoming, when, about the year 1871, the scientific world was startled by an announcement from Mr. Daintree of a very singular and unexpected circumstance that he had observed bearing on the question. Professor Ulrich states the matter thus: "Mr. Daintree's discovery consisted in the fact that a speck of gold lying in a solution of chloride of gold increased several times its original size after a small piece of cork had accidentally fallen into the solution."J Here, then, appeared to be the " one thing that was wanted " to show how gold can accrete gold to itself in a natural way, and discovered by one of those accidents that luckily had an observer, and one who was competent to see the full significance of it. Thus, it appears that all we require for this accretion of gold on gold in our drifts is a weak solution of gold in an acid, organic matter therein of a somewhat unstable character, and metallic gold. I say here "it appears," for it will be noted there is a tantalising lack of detail, of precision, and, indeed, of certainty, in the description of the circumstances of the case that detracts greatly from the value of the evidence ; and yet there was such a promise of useful knowledge to be gathered by a careful

* Trans, and Proc. of the Royal Society of Victoria, vol. ix., p. 53. t It appears very improbable that nuggets of reef gold can ever have any notable proportion of thoir silver substituted by gold when they get into our drifts, as the atomic volumes of the two metals are practically the same. J " The Goldfields of Victoria," by R. Brough Smyth, Secretary of Mines, Victoria.