The extraction of reef gold from its matrix is a much more complicated process, and the problem how most effectively to obtain that great desideratum—­a complete separating and saving operation—­is one which taxes the skill and evokes the ingenuity of scientific men all over the world.  The difficulty is that as scarcely any two gangues, or matrixes, are exactly alike, the treatment which is found most effective on one mine will often not answer in another.  Much also depends on the proportion of gold to the ton of rock under treatment, as the most scientific and perfect processes of lixiviation hitherto adopted will not pay, even when all other conditions are favourable, if the amount of gold is much under half an ounce to the ton and even then will leave but a very small profit.  If, however, the gold is “free,” and the lode large, a very few pennyweights (or “dollars,” as the Americans say) to the ton will pay handsomely.  The mode of extraction longest in vogue, and after all the cheapest and most effective, for free milling ores where the gold is not too fine, is amalgamation with mercury, which metal has a strong affinity for gold, silver, and copper.

As to crushing appliances, I shall not say much.  “Their name is legion for they are many,” and the same may be said of concentrators.  It may be old-fashioned, but I admit my predilection is still in favour of the stamper-battery, for the reason that though it may be slower in proportion to the power employed, it is simple and not liable to get out of order, a great advantage when one has so often to depend on men who bring to their work a supply principally of main strength and stupidity.  For the same reason I prefer the old draw and lift, and plunger pumps to newer but more complicated water-lifters.

On both these points, however, I am constrained to admit that my opinion has recently been somewhat shaken.

I have lately seen two appliances which appear to mark a new era in the scientific progress of mining.  One is the “Griffin Mill,” the other the “Lemichel Siphon Elevateur.”

The first is in some respects on the principle of the Huntingdon Mill.  The latter, if the inventor may be believed and the results seem to show he can be, will be a wonderful factor in developing not only mining properties where a preponderance of water is the trouble, but also in providing an automatic, and therefore extremely cheap, mode of water-raising and supply, which in simplicity is thus far unexampled.  Atmospheric pressure alone is relied on.  The well-known process of the syphon is the basis, but with this essential difference, that a large proportion of the water drawn up to the apex of the syphon is super-elevated to heights regulated by the fall obtained in the outlet leg.  This elevation can be repeated almost indefinitely by returning the waste water to the reservoirs.

The Lemichel Syphon is a wonderful, yet most simple application of natural force.  The inlet leg of the syphon is larger in diameter than the outlet leg, and is provided at the bottom with a valve or “clack.”  The outlet leg has a tap at its base.  At the apex are two chambers, with an intermediary valve, regulated by a counterpoise weighted lever.  The first chamber has also a vertical valve and pipe.