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 Royal 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, that 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. R. 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.”^*

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 tantalizing 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 investigation of the case: that I among others attempted it, but, for myself, was quite unable to realise the promise—in fact, I was unable to repeat the phenomenon as described. I got nothing to indicate that gold is nuclear to itself in solutions that contain organic matter, whether in a solid or in a dissolved form. The effect of such matters (organic), I found, was rather to disperse any gold it reduces than to concentrate such gold in a nuggetty form.

The results of these researches of mine were contained in a paper which was read before the Wellington Philosophical Society in 1872, and from this paper I make the following quotations:^† “So far, therefore” — alluding to results just stated —“gold reduced from solution of its chloride by aid of organic matter, such as cork or wood, does not in the manner of its deposition exhibit such a notably selective power for metallic gold as the description of Mr. Daintree's results lead us to suppose. It does not, indeed, show any such selective process at all—that is, to a greater extent than can be attributed to the action of surfaces generally regardless of their nature; and in support of this I believe I am quite correct in stating that the whole sum of our experiences (omitting those of Mr. Daintree) is directly against this theory…. So far as I am aware, we only produce by these means (organic matters) fine incoherent powder—minute crystals or films of exceeding thinness, nothing at all nuggetty.”

I have since learned that Mr. Cosmo Newberry, late Analyst to the Geological Survey of Victoria, has confirmed the general accuracy of these assertions of mine by showing

that gold is not nuclear to gold under the circumstances given by Mr. Daintree.

Thus it seems that, after all, as yet we have got nothing more than the hazy, crude idea of the Old-World digger of the growth of nuggets in our drifts, an idea that many geological facts support, while others are antagonistic to it. And this growth of the nugget has been asserted by scientists to have been produced by nuclear action. Nuclear action, indeed! alias nuclear force! I take it to be of the same misbegotten fraternity as the centrifugal and centripetal forces of our oldest school-books—those learned terms that only obscured the truth they were invented to show.

A long period of time again passed; the subject had apparently dropped out of mind, when a second time the scientific world was startled by a communication on the same subject, and for the same object. This time it was Mr. Charles Wilkinson, of the Geological Survey, and evidently the theory of Mr. Daintree, above detailed, had worked in his mind, and inspired its operations—the possible or probable nuclearity of gold for gold as in our drifts (that is, under natural conditions) had yet to be proved. But, as he thought, why limit the problem to gold? Why not try some of the native minerals that frequently exist along with gold? Filled with this idea, he, after making numerous unsuccessful experiments, at length tried the metallic sulphides, and was handsomely rewarded. He had, as he thought, got the key to the problem. His results are given in a paper entitled “On the Formation of Gold Nuggets.”^* Shortly stated, this paper informs us that cupreous and iron sulphides, arsenical pyrites, galena, zincblende, stibnite, wolfram, and molybdenite act as gold does for nuclei to gold as reduced and precipitated from its chloride in water by organic matter.

The accuracy of these statements thus given by Mr. Wilkinson was soon afterwards vouched for by Mr. Cosmo Newberry. Here, then, at last it appeared that this so-called “nuclear action” of a solid substance for gold had been sheeted home—that certain kinds of minerals can accrete, can attract, as it were, unto themselves the minute particles of gold that organic matters liberate from auric chloride, and mould these to the coherent, the crystalline, the massive form of the metal as we see it in the nugget; and thus the idea of a nuclear action of gold itself for gold, as Mr. Daintree's observation favours, receives apparently a further accession of proof.

These results that Mr. Wilkinson obtained very much in-

terested me, and I repeated them with such variations as my previous knowledge of the subject, and particularly of the dispersing effect of organic matter on gold solution, led me to make.

Leaving out, then, the organic matter, I simply introduced a crystal of pyrites into the weak solution of gold trichloride in distilled water, when after a two-hours contact I found that this crystal was completely gilded over. The metal thereon was lustrous and coherent, and the crystal had all the appearance of solid gold. I afterwards found that the metallic sulphide arsenides generally as used without organic matter bad the same effect as pyrites. Thus it was proved that derelict atoms of gold are not required for the accretion of gold on gold in the concrete form which obtains in our auriferous drifts.^*

The explanation of this liberation of gold from its solution is simple. For this we must look upon the gold in solution as being a part of the combination—hydrochloride of oxide of gold, or hydrated trichloride of gold, the oxygen of which oxidizes both the sulphur and the metal of these sulphides so as to leave the gold upon them at the scene of action in the metallic state.

But this, though explanatory of the reduction of gold, is not explanatory of the fact that the gold thus reduced is (the greater part at least) close and reguline, in place of its particles being more or less discrete, as they would be in the case of a deposit by simple reduction. This, I find, however, is explained by the fact that after the first few seconds of contact of the metallic sulphide with the auriferous solution the gold is deposited electrically—that, in fact, an electrical current is produced by the oxidation of the sulphide, and so the process is an electrolytic, an electro-gilding one.

In all this we have a proper rendering of the terms “nuclear action” or “nuclear effect” if we wish to keep them up in all their absurdity—gold can be nuclear to gold only as under the influence of an electric current.

Thus it comes about as probable—indeed, as a certainty, I think—that if the nuggets and particles of gold in our drift formations do accrete gold—do exercise a “nuclear effect,” as it is termed, for gold—it is under the directing influence of an electric current, or perhaps I should say it is simultaneously with the production of an electric current at the seat of action. In regard to this, we have seen that in our metallic sulphides as associated with auriferous solutions we have the

means for producing electric currents — that is, electrolytic action; but, except in the case of our deeper-seated reefs, we do not get these sulphides, and, as in contact with the gold of our drifts we only get it rarely, therefore the question we have is this: Does there exist a general agency in these drifts for the production of electric currents in or in juxtaposition to the gold of these drifts? This question that I have just worked up, and in such a way as to incorporate here the historical facts above stated, I shall endeavour to answer, and in the affirmative. I shall, as I think, show that there are in these auriferous drifts generally the means whereby the electro-deposition of gold on gold can be accomplished, and this in a general, a natural way; and I shall also endeavour to show what these means are.

Now, it is on record^* that in 1876 I communicated to this Society a knowledge of the fact I had just then discovered, that electrical currents are generated by platina when paired with graphite in alkaline and also in saline solutions; a fact that, by the way, I afterwards found had just a little prior to this time been announced both by Professors Becquerel and Gaugain^† in publications to which I had not access for years afterwards. At that time I attributed these currents to chemical action at the surface of the platina, and not to a mere polarisation of the metal, as Professor Becquerel maintained. Thoroughly believing my view of the case to be correct, it occurred to me, in view of the question before us, to carry my investigation of the subject far enough to ascertain whether any of our noble metals do give, in alkaline solutions, electric currents sufficiently strong and persistent to decompose acid solutions of gold and deposit the metal in the form in which we find it in our auriferous drifts. For my first—my tentative—experiment I made choice of platina as the metal that, if it did give me any results at all, would exhibit them with unmistakable clearness. Thoroughly cleaning a wire of this metal in suitable acids, I waxed it to within ½ in. of each extremity, and then plunged one end of it in a weak solution of caustic potash, and the other end I placed in a very weak solution of auric chloride, making the interpolar connection between the two vessels containing these solutions with stiff gelatine in a U-shaped glass tube, when, after the expiration of four hours, I found the platina wire was gilded up to the waxed part, while in twenty-four hours all the gold of the solution had been electro-deposited on the platina wire. The gold was in the highest degree solid, lustrous, and reguline.

This was very encouraging, so I at once continued the

investigation by experimenting upon gold, and the results of this I herewith state as shortly as I can, and in the order that I obtained them:—

1. When pure gold in weak or strong solutions of an alkali is electrically connected with gold in a weak solution of the terchloride of that metal a deposit of gold (out of the metallic solution) upon the gold therein occurs, and this gold is both lustrous and coherent.

2. When the ordinary acids, such as hydrochloric, sulphuric, and acetic acids, also the neutral salts generally, are substituted for the alkali the same effects are produced, but at a much slower rate.

3. Common spring water and distilled water may be substituted for the acids with similar but, of course, far less pronounced effects.

4. The same results as those above stated are also to be obtained if the solution of gold is feebly alkalized with an alkaline bicarbonate.

5. No such deposit occurs if the auric chloride or bicarbonate is replaced by an alkaline aurate.

6. A large sheet of gold in the auric chloride, coupled with a small sheet of gold in the same solution and of the same strength, deposits gold on the small sheet.

7. With gold in a weak solution of the auric chloride, as against gold in a strong solution of this salt, this metal is precipitated on the gold in the strong solution.

8. If gold or platina in auric chloride be connected with platina or gold that is in good contact with any ordinary soil it receives a deposit of bright solid gold thereon in a few hours, while the metal that is in the soil becomes coated with a thin but continuous film of peroxide of iron in most cases.

9. Gold in an alkaline solution is electro-positive to gold in acid solutions generally.

In every case the gold or the platina that stood in the auric chloride solution was coated with wax to well below the surface of the liquid, to guard against any irregular deposit of gold brought about by differences in the surroundings of the metal.

It was proved that the gelatine used for the interpolar connections in these experiments had no part (by its deoxidizing properties) in the production of these metallic deposits.

These results, as a whole, show very clearly that gold can be nuclear to itself in the popular meaning of the term—that, in fact, it can either of itself, or assisted in some way that at present we do not understand slowly build gold upon gold in that solid coherent form that our nuggets are in. They

show, besides, that, whatever the means are by which this is produced, these will exist throughout-all the drifts in which native gold occurs. Thus, any particle or nugget of gold lying in the bed, or partly in the bed, of a stream that contains gold in solution, will certainly become coated with gold, and this because it is in such a position that the upper and lower surfaces of it are in a saline solution of a different nature, the water being acidic from the presence of free carbonic acid, while the sand and earth are more or less alkaline, the alkaline solution, as we have seen, being especially favourable to the liberation of gold from acid solutions of it. This liberation is a chemical act, and therefore is accompanied by an electric current, by which the gold is electro-deposited on the upper part of the particle or nugget of gold.

All this signifies that for the deposition of gold we have here there must be the “seed-gold,” or auriferous nuclei, to start with; but it is not necessary to go to the reef for this. In any strong proto-compound of iron or metallic sulphide, or even organic matter, we have in conjunction with such auriferous water the means to insure the small particles—the nuclei, the seed-gold—necessary for this metallic accretion.

Thus far I have carefully restricted myself to showing the single fact that particles and nuggets of gold in our drifts must generally enlarge by the accretion of gold thereon from its solution in the waters which permeate these drifts: the question as to how these accretions are effected, or, rather, what initiates the process, I have abstained from trenching upon; but this question I now, in due course, discuss.

We have seen that during these deposits of gold that I have shown to occur under the conditions here cited currents of electricity are generated—that, in fact, it is by these currents that the gold is deposited in the concrete—the massive form in which nuggets are in. All I have to do, then, is to show how these currents are produced.

I will note here, in the first place, that these currents are of a different class to those described by Professors Becquerel and Gaugain, which are currents produced by immersing the plates of platina in different physical conditions into acid or alkaline solutions or distilled water, and are acknowledged by these investigators to be merely ephemeral, and so are not of that determinate character necessary for the work here demanded of them.

Now, in our Transactions for 1875 I showed that platina in an alkaline solution is electrically positive to platina in an acid or in a neutral solution. The currents, however, obtained in this way appear to be like those treated by Professor Becquerel, above described; but I found that if the platina, in the alkaline solution were coupled with platina or gold in

nitric acid or in auric chloride the electric current was not of an ephemeral character, but, on the other hand, was regular and continuous, so long as there was nitric acid or the gold salt present. The currents, then, may properly be termed permanent, and, being so, the difficulty of accounting for them appears greater than in the case of Professor Becquerel's currents, for they cannot be properly referred to any polarization of the surfaces of the metals or to any condensation of gas thereon, as he supposes takes place for the production of his currents, but. they demand the even, the constant, expenditure of some power, and which, under the circumstances, must involve chemical action, and this absolutely contiguous to the metal—at least, to one of the metals—that is, to one of the poles used. Being so, then the only thing left to do is to determine what are the two substances to which this chemical is due, and what substances form this chemical combination in the immediate vicinity of the metal. Now, it is quite certain that neither of these substances is the platina or the gold itself, for they do not suffer, to any determinate extent, loss during the reaction, nor can they be oxidized except very superficially. (See addenda for further notes on this matter.)

The chemical action, then, that is necessary to produce the current must be produced in one of the three following ways:—

1. By the (chemical) combination of the free oxygen and nitrogen gases present as air at the surface of the metal.

2. By the oxidation of nitrogen by the oxygen of the water.

3. By the oxidation of the alkali or the acid present by the oxygen of water.

Now, in regard to the first theory, it has to be considered that the deposition of gold in these cases being, as we have seen, an electrolytic effect, an electrolysis of both solutions is demanded, and I cannot see how the mere combination of oxygen and nitrogen could effect this; the only result would be a minute production of heat.

We have therefore, as I conceive, only the two remaining theories to consider, and, as both involve a decomposition of water, it is only a question whether the nitrogen gas present is oxidized, or the potash is oxidized to the binoxide, or the acid is further oxidized by the oxygen of the water so as to produce the chemical action—the electrolytic effect—that we require. This question I have to leave for the present undetermined for want of leisure and suitable apparatus, but I shall take the matter up again shortly, and the results of this further investigation I will acquaint you with in due course; meanwhile I will here describe the results of two experiments made to settle the question.

Two platina plates, one in a gold solution the other in a potash solution, were connected through a galvanometer, and the deviation of the needle marked when it had attained constancy. A stream of oxygen was then passed through the potash solution, when it was ascertained that the deflection of that needle was neither notably increased nor decreased, a fact that appears to prove that it is not the nitrogen which is oxidized.

In another experiment I found that the potash solution had not bleached organic matters—litmus paper, &c.—at all, even after the deposition of gold had extended over eight hours.

These results are conflicting. However, these experiments are merely of a tentative character; but, as I say, I hope very soon to be able to make further and complete investigations on the subject

There is one circumstance in connection with the alleged discovery of Mr. Daintree of a nuclear action of gold for gold as liberated by organic matter from its chloride that, in conclusion, I would like to make a few observations upon, and this in justice to the memory of that scientist. It may be remembered by some here that I did not hesitate to avow a certain amount of incredulity as to the alleged growth of the particle of gold that Mr. Daintree left in the solution of gold that he had prepared; but just lately, in further considering the case in connection with the facts that I have here stated before you, I could not but think that probably, after all, this scientist's statement as to a certain palpable increase in the size of this gold residue might be correct. The question was, then, if correct, to what was this increase due? Now, it did not appear very likely, under the circumstances, that all this increase was due to differences in the strength or nature of the solution itself whereby action would, as we have seen, be set up; so it occurred to me to try whether or not contact of the gold with the vessel itself had anything to do with it. Binding, therefore, some clean platina wires round small pieces of white porcelain, glass, and white quartz respectively, I placed these pairs in the trichloride of gold, while a similar wire I wrapped in filter-paper and immersed it in the same solution of gold, when in four hours I observed that the wires that were attached to the porcelain and glass were feebly gilded, whilst that attached to the quartz was thickly gilded, but the wire unattached did not exhibit any trace of gold thereon. Gold in place of platina in these experiments also accretes gold to itself, which is clearly revealed by the altered appearance that in a few hours it presented.

As the quartz was of the pure white variety I was led at