CHEMISTRY, AS APPLIED TO GOLD GETTING.

West Coast Times, Issue 614, 12 September 1867, Page 2

CHEMISTRY, AS APPLIED TO GOLD GETTING.

(FEOM THK GREY BIVEB ABGTTS.)

At no former period has chemica science rendered rnqre valuable aid to practical industry than within the last few years. The most ponderous processes of metallurgy and'mechanics, and the most delicate operations of skilled labor, have arrived at their present stage of perfection by means "of the researches of scientific men, The discovery of new agents has wonderfully simplified and economised manufacturing industry ; and although the grand results achieved are frequently the fruits of many previous failures, every asserted discovery, however incomplete, .should receive the test of application. The treatment of ores and substances containing the precious metals has naturally been a favorite subject with ohemists, and multitudinous processes of varying character, have been proposed, many of which have proved effectual, but not of practical value — they have served to illustrate a theory, but not an economic fact ; and some have fulfilled every condition of utility. Of the latter class, probably none has been presented under more fayorabie prognostications or with greater evidence of practical value, than the admixture of sodium with mercury so as to increase the affinity of the latter metal with gold. Hitherto quicksilver has been employed as the only agent by which particles of gold too fine for recovery by the ordinary process of gravitation in water can be saved. The gold, as we are all aware, amalgamates with the quicksilver, and is again liberated by the evaporation of the mercury. But it has been ascertained that the properties of mercury as anamalgamating agent are liable to deterioration from a variety of causes — the oxidation of the mercury itself, or the presence of other chemical elements in the ore treated. In consequence of this attenuation of the powers of the mercury, much of the gold escapes, .and is lost ; it having been calculated that as much as 30 per cent, of the precious atoms, on the average, are allowed to run off with the waste ore or sandj Chemists have set themselvos to work to discover an antidote for this " sickening" — as it is technically termed — of the mercury, and the result is that it has been demonstrated beyond doubt, that the admixture of sodium in certain quantities has the effect of increasing the amalgamating properties of the mercury, and of retaining them ia full force throughout the process. It is impossible to over-estimate the value of this discovery, and although at present much experiment is necessary to estabblish the exact method of treating the Various auriferous substances w^ththQ

new agent, it has been shown that it is capable of effecting an enormous saving of the precious metal. Most of our readers will be familiarised with the general features of the discovery, and we cannot ourselves pretend to any other knowledge than that which is supplied to us by the various published reports on the subject. In our issue of

tbe 6th July, we republished from the *' Journal of the Society of Arts" a very i iteresting and complete account of the properties of the sodium-amalgam, and the various processes under which it had been proved to be effective. "We intend to reproduce this article in our Saturday's issue, in order that our mining readers may become possessed of the best information on the subject. The circumstance that a quantity of the amalgam has been imported by one of our' local tradesmen makes it all the more desirable that we should endeavor to afford all the information in our power. The sodium-amalgam imported by Mr Williams is that prepared by Professor Crookes, F.E.S., of London, to whom the discovery of the practical Application of sodium to the extraction of gold is attributed. The amalgam is prepared of three different kinds — A B and C — the last of which are to prevent the flowering or powdering of mercury when the gold is intermixed with sulphurates. The first (A) is most powerful in increasing the affinity between mercury and gold, and in bring-

ing back sickened or floured mercury

into a fluid state. The patentee, in his -directions, states that the proper quantities of the several amalgams can only be fixed by experiment; but he gives the following general directions : — I therefore recommend that at the commencement one part of amalgam B or amalgam C being dissolved into thirty parts of the mercury which is to be used in the goldamalgamating vessels, or triturating or grinding machines, and the effect wliich it produces on the mercury noted from time to time during the operation. If the mercury retains its brightness and activity to the end of tbe operation it is a sign that either sufficient or too much has been added, and a second experiment should be tried with a diminished quantity of the amalgam. But if the mercury be "floured," or "sick," or if any be lost, more amalgam may be added until the best proportion is arrived at. Amalgam B will generally be found to be effective, but if the ore contains an excess of any mineral which has a deleterious action on the mercury, more especially if this mineral contuns bismuth, ifc will be advantageous to employ amalgam C instead of amalgam B. When the best proportion of amalgam B or qT amalgam C is found out, I advise the occasional introduction of some quantities of amalgam A into the mercury already containing amalgy -^ E or amalgam 0 to 1000 parts of mercury. This quantity of amalgam A can be added every three, six, twelve, eighteen, or twenty-four hour, according to circumstances ; but one charge of amalgam B or amalgam C will usually be sufficient for the mercury for several days'of a week. In some circumstances it may be found advisable to add amalgam B or amalgam C every day or two, but a little experience and comparison with the results obtained in previous trials will soon show how these agents are best utilised. >

With iegaf^ to applying the amalgam to the surface o\ copper-plates, he says : — By employing amalgam A in coarse powder, and sprinkling it over the wetted metallic r surface whirh it is wished to amalgamate, and then rubbing it over 'with a"Uttle clean mercury, a firmly adherent and brilliant coating of mercury will be given to the metal. Not only can copper be amalgamated in this manner, but the same result is produce.d on galvanised iron (iron coated with a tlu'n layer of zinc), or tin plnte (iron coated with a thin layer of tin), lead, and less perfectly on iron and steel. In all cases it is advisable to preserve the effective surface and the amalgamating energy of the mercury on the metal by an occasional sprinkling of powdered amalgam A, applied from time to time as required. We have not space to devote to a lengthened review of the experiments, but we have said sufficient to show the general character of the discovery, and the principles of using the new agent, and now that the material is within the reach of the miners, we hope to be able soon to chronicle successful experiments in this district. We may mention as an instance in proof of the value of the sodium-amalgam that at the present time gotd is being profitably extracted from the Fingal quartz-reef, in Tasmania, which could not otherwise be saved at all. The stone from that reef does not show any gold to the eye, but by means of the sodium-amalgam it is made to pay. We may conclude by stating that any person desirous of doing so can peruse the various reports on the sodium process by calling at the office of this paper.