not satisfy me. You will remember in one part of his paper Mr. Thompson objects to the predominance of water in the earth, and states that if that were the case, then the specific gravity of its solid parts must be nearly that of gold. Now, were that so, not only should we have a new Plutonic theory! but it would really after all be only in accordance with what was stated in the address of Mr. Grove, as President of the British Association, last August-namely, that instead of the heaviest matter of the earth being near its surface (as we have long been taught), it is probably more solid and heavier as it gets nearer the centre. But apparently Mr. Thompson's sole reason for rejecting this, is merely that it is contrary to the Newtonian theory as to the mass of the whole earth; for it is upon that theoretical assumption, and not upon facts, that the whole reasoning is based. It is enough for me to point out, that at any rate, that theory has not stood in the way of Mr. Grove propounding, as now most probable, what is not only contrary to the Newtonian doctrine as to the earth's mass, but also to the nebular notion that the earth's centre is filled with matter in a state of igneous fluidity. In conclusion, I am obliged to say that if we consider that MM. Daubrée and Bischoff made certain experiments with granite which convinced them that it is a watery crystallization, and also that they have brought over the leading geologists to this view, although it was contrary to all their preconceived notions and previous teaching, I think it was incumbent upon Mr. Thompson to have noticed the experiments of these eminent chemists, and, if he could, to have shown where they were defective and faulty; and not merely to have made a detached and single experiment of his own, which appears to prove very little, and even that little, in my opinion, to be rather against what he deduces from it.

Mr. HOPKINS.-I can see clearly, from the observations of Mr. Thompson, that he has been making experiments from cabinet specimens of granite. Suppose you were to make experiments from cabinet specimens of wood, to ascertain something as to the sap of a tree in its living state, you would obtain very strange results! Now, if you want to ascertain the real constitution of granite, you should study the granite in situ. For instance, in one place you may have a granite undergoing change. That granite is composed of hornblende, felspar, mica, and so on, and is undergoing lamination. If you take a piece of that granite, and cut a block of it, and weigh it, you will find that it loses weight after exposure to heat, just the same as minerals. We allow so much for water, and we call that water mechanically combined. Granite is saturated with water; it is always saturated, and is not a mere dry block.

Rev. W. MITCHELL.-May I ask you, Mr. Hopkins, to answer one question, as you are well acquainted with deep mines, Whether you can go to any depth where you do not find water; and whether water is not the greatest enemy of the miner?

Mr. HOPKINS. It is the most difficult thing the miner has to contend with, and you cannot go to any depth without finding it. Wherever you go, you come to water, whether in granite or any other formation. With refer

ence to the constitution of granite, if you take separate crystals, you will also find that each crystal has a certain proportion of water chemically or mineralogically combined; and if you drive it out, the crystal becomes opaque, and loses weight, the quantity varying from two or three to twenty per cent. Without water, crystals are not formed, especially rock-crystals. Again you may have granite, with gold in saturation. In another place you will find the gold becoming gradually developed out of the granite as the granite undergoes changes, and coming out like large round balls. Elsewhere you find a little gold in dissemination, but not like the other. There is change constantly going on; the condition of the rocks is never stationary, but it either changes into lamination, or into fractures, something like the bark on the trunk of a tree. Now, I say we have such an immense accumulation of facts, that we ought now to insist upon facts; and not go on trying to find out what is in the centre of the earth, and so on. Let us attend to facts as we find them, and see what we really have; and let us leave theories for the future. I will add one or two words with regard to minerals. I have no hesitation in stating that I will go to any rock and say what it contains by looking at it. If you let me see a good surface of it, I will state whether it contains gold, silver, tin, and so on. I am speaking as to the metal the rock will contain, and not as to the quantity of the metal, for that will depend on the amount of deposits and accumulations, but I am referring only to the nature of the constituents.

The CHAIRMAN.-I shall only make a few observations from my own point of view, in confirmation of what Mr. Hopkins has said with regard to the formation of granite. In doing so I may express some of my objections to the theory advanced by Mr. Thompson. The experiment performed by the latter gentleman on a small scale, as Mr. Hopkins has reminded us, is wrough out by nature on the most gigantic scale. Wherever we find active volcanoes, we find them melting granite, or some other primary rock. Lava, obsidian, pitchstone, and such-like volcanic products, are but molten primary rocks. Now I ask what analogy do any of these substances bear in their structure to the so-called primary rocks? Are they anything like granite, for instance? Mr. Thompson admits that the structure of granite could not be formed from any of these substances by slow cooling. That I take to be an important admission. I cannot believe it is produced by quick or any intermediate rate of cooling. We have not to go far even in London for a practical demonstration of the structure of the primary rocks. Our bridges and public buildings show us that granite is composed of well-formed crystals of several distinct minerals, interlacing one another in every direction; crystals of quartz, mica, and felspar. On London or Southwark Bridge you may see crystals of the latter substance as large, or larger, than your hand, presenting to the casual observer the appearance of large fossil bones. The constituents of granite not only contain water chemically united to them, but they also contain water mechanically diffused, a fact which can hardly be reconciled with their production by crystallization from a molten mass. Now let us consider the crystalline constituents of granite--we have crystals of quartz,

consisting of silica in a state more or less free from admixture with foreign substances. Then we have the crystals of mica and felspar, the most composite of mineral substances. These three substances are distinct from one another in crystalline and chemical composition. But then the micas and felspars admit of the greatest and most puzzling varieties of chemical constitution; one chemical element taking the place of another, without altering the crystalline character of the mica or the felspar in which the change of composition is found. We may have some conception of the composite structures and varieties of these minerals, when we state that nearly all, if not all, the metals and the mineral constituents of the sedimentary rocks may be found in the granites or other primary rocks. We have potash and also soda felspars. In the micas as well as the felspars we have not only the principal constituents, silica and alumina, but also soda, potash, lime, iron, magnesia, and water, replacing each other with most puzzling variations. We all know how gold is diffused through the quartz of some kinds of granite. The microscope is said also to reveal native iron among the constituents of granite. Doubtless all the metals and other minerals found in the cracks and crevices of the primary rocks were once in combination with these rocks. But I never could form any clear conception of the origin of metallic and mineral veins till I read Mr. Hopkins's work on the subject. Very high geological and mineralogical authorities used to speak of gold as the most recent of all the metals ;-how more recent than others, I could not conceive. Some went so far as to imagine some recent geological event, when, as it were, a golden shower had fallen from heaven to earth! The experiments of Daubrée and Bischoff have proved the mechanical and chemical combination of water in granite. Though the authorities of the Geological Society were not convinced by Mr. Hopkins, their faith in the igneous origin of granite was first shaken, I believe, by my friend Mr. Clifton Sorby's microscopical researches. By investigating microscopically the minute bubbles in crystals, he was able to determine whether the crystal was formed from an aqueous or some other liquid solution, or produced by cooling from a molten mass. With regard to Mr. Thompson's assumption of the insolubility of silica in water, the geysers in Iceland afford a direct refutation of this. How, again, without the solubility of silica, can we account for the formation of silicified woods, without injury to the most delicate vegetable fibres? Dr. Bowerbank has shown that the most delicate structures in sponges (which he had found destroyed by decomposition only a few hours after the death of the sponge), are faithfully and perfectly preserved in the flint. Before electro-metallurgy was discovered, we could form no idea as to the method nature takes to separate metals from the rocks through which they may be diffused. We have now, however, learnt the power of electricity in separating metals from the aqueous solutions of their salts. Soon after the discovery of this fact, a copper electrotype was produced without any artificial battery, by imbedding wires in two different strata of a mine, and using the galvanic current thús produced. Here then we have a demonstration of the electro-magnetic action of the earth, and of its power in the formation of mineral products. This

ORDINARY MEETING, JAN. 7, 1867.

THE REV. WALTER MITCHELL, VICE-PRESIDENT, IN THE CHAIR.

The minutes of the previous Meeting were read and confirmed; and the Hon. Secretary then announced the names of the following Members and Associates who had been elected since the first Meeting at the commencement of the Session:

MEMBERS:-Benjamin Bond Cabbell, Esq., M.A., F.R.S., &c., &c., Bencher of the Middle Temple, J.P., and Dep.-Lieut. for Middlesex, 52, Portland Place, W. (VICE-PATRON and Life Member.)

William Henry Elliott, Esq., 10, Claremont Crescent, Surbiton Hill, S.W. (Life Member.)

Thomas Ball, Esq., Bramcote, Notts; Charles Lloyd Braithwaite, Esq., Kendal, Westmoreland; John Colebrook, Esq., M.R.C.S. Eng., late H.M. Madras Army, 31, Moore Street, Chelsea, S.W.; Rev. William Reyner Cosens, M.A., Oxon. et Cantab., Incumbent of Holy Trinity, Westminster, 10, Bessborough Gardens, Pimlico, S.W.; Rev. M. Davison, 5, Lansdowne Place, Lansdowne Road, Hackney, N.E.; Charles Deacon, Esq., 5, Orsett Place, Westbourne Terrace, W.; Thomas Foljambe, Esq., M.A., J.P., and Dep.-Lieut. for West Riding of Yorkshire, Acomb, near York; Alexander Gailey, Esq., Harengey Park, Hornsey, N.; Sydney Gedge, Esq., Mitcham Hall, S.; Bruce Goldie, Esq., Russell Street, Chelsea, S.W.; Thomas Gray, Esq., H.M. Civil Service, Assoc. I.N.A., 9, St. Martin's Road, Stockwell, S.; John Hall, Esq., Bondicar House, Blackheath, S.E.; James Peddie Harper, Esq., M.D., Edin. Univ., M.R.C.S.E., Clydesdale Villa, Windsor, Berks; Rev. Sir W. R. Tilson-Marsh, Bart., M.A., Oxon., Oxford and Cambridge Club, Pallmall, S.W.; Arthur C. Rainey, Teignmouth, Devon; John Henry Sadler, Esq., 34, Norfolk Road, Brighton; John Shaw, Esq., M.D., Viatoris Villa, Boston, Lincolnshire; William Stewart, Esq., of Glen Stewart, Prince Edward's Island, 12, Cottage Road, Eaton Square, S.W.; James E. Vanner, Esq., Stamford Hill, N.; William Vanner, Esq., Stamford Hill, N.