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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 determined 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 polarisation 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