Year: 1877

drogen necessary for the formation of the

 sulphide and the alkali. neceSsaiy for its

 solution we have, in the thernial waters

 connected with so many mineral veins, the

 necessary material for the solution If the

 metal. This part of the discovery was con- vincingly suSt aimed by Sonsdat's discovery

 that the water of the ocean contains gold to the amount of somewhat less than one gram to the ton Trihing as this propor-

 tion is, we have only to assume uniform

 strength for tue waters of all the oceans

 to have a reservoir of bullion containing

 more metal than all which man has ex- tracted from tie earth There is little doubt that even this weak solution will some day be utilized as d source of gold:

 The immensity of the quantity thus dis

 solved in sea water is proof that the

 work of solution has gone on for an incon-

 ceivablt length of tune.

 The solubility of the metal in water be-

 ing thus proved, it is next in order to con-

 slider how it can be deposited, and the sec

 ond startling announcement in this series of discoveries was the fact that nuggets of gold grow; that is, they increase by accre-

 suggested, by organic matter, by sulphate

 of iron and tv pyrite, a mineral containing sulphur and iron in nearly equal parts. Experiment proves that this last substance

 has the power not only of precipitating the dissolved gold, but also of exerting nuclear action, by means of which the fresh portions of precipitated metals ad-

 here to that which has already been formed

 instead of being disseminated in powder

 as happens when sulphate of iron or or

 ganc matter has been the reagent. Pyrite

 Is very common mineral, and is an almost

 invariable constituent of vein matter. The

 soil of all the gold bearing strata contains

 large quantities of it ill the form of sand

 and gravel, the result of the contribution

 of solid deposits. If we conceive stream of weak gold solution flowing constantly

 through layer of loose earth which con

 tains nuggets of pyrite, we have the con

 in the strata where the masses of gold are now found In such state of affairs the nOdules of pyrites would first reduce min- ute spangles of gold, which would adhere to the pyrite, and gradually increase by successive depositions until continuous film of some size is formed, and voltaic pair is constituted, of which the pyrite forms the positive anu the gold the nega- tive element The deposition of gold now goes on precisely as in an electrotyping bath, a constant and orderly increase Of the thickness of the gold plate taking place until the mass of pyrite is oXidized and its acittulating power expended. Tie amount of gold which any given mass of pyritc may precipitate before exhaustion is easily calculated and it is found that he largest known nugget may have resulted from the action Of comparatively small pieces pyrite. Thus, the Welcome nug- get, which weighed 152 pounds, required no more than twelve pound lump of py- rite for its formation, and Jumps of this | size are extremely common.

 Tire formation of the large nuggets hay ing been traced, with so much probability; | to chemical action in the place where they | are found rather than to vein origin, it i remains to consider whether the fine golG | of the placerS is also due to this chemical . action, or whether that has been obtained . by the breaking up of veins. Just as the fact that large nuggets have never been found ir veins was almost conclusive proof cf different origin for them, so differ ence in composition is equally significant of the origin of placer gold. Vein gold is never so pure as that found in the gravel. IL contains very much more silver, and this is ascribed to the fact that silver is not so readily precipited by p-rite from acid solutions as alkaline. The subterra- mean alkaline and sulphur0us water holds both gold and silver in solution, and so long as the water is retained in the earth its alkalinity is preserved so that the pre- r;p .tation of the two metals goes on with equal thoroughness and rapidty in veins; put when the water reaches the atmOs- Dhere its character changes gradually by .hc oxidation of it's own constituents, and by the solution of organic and mineral lcids. It steadily loses alkaii and becomes lcid. in which condition only the gold is orecipitated. This would account for the greater purity of surface gold, and this eads to the supposition that the gold Of ,lacers is mostly formed in situ'" by pre- .ipitation. Such are the conclusions of dr. Skey, analyst to the New Zealand Geo. ogical survey The behavior of pyrite oward solutions containing both gold and {