The weekly Arizona miner., 1872-02-17
Absorption of Sulphur by Gold.

l Mir. William Skcy, analyst to the geologi- cal survey of New Zealand, has published an interesting paper on tine absorption of sulphur | by gold, and its effects in retardlng amaiSa nation. While investigating the causes oi the reported loss of gold during the process of extraction at the Thames gold fields, he oD- served that much of this loss could scarceiy be referred to any of those causes generally supposed operative for it. He therefore test ed the actual condition of the natural sur l faces of numerous specimens of Thames gold, | in respect to their behavior with mercury, and examined further than has hitherto been done into its compartment with several Oi those substances likely to be associated with it in natural way. The results of these examinations, says the 1 San Francisco Scientific Press, are minutely recorded in his paper, and the following short extract of them is taken from the London Chemical Ners The author finds l. That numerous samples of bright, clean looking gold, of all degrees of fnencss, refuse to amalgamate on any part of their natural surfaces, though taken directly from the reef and untouched by hand.
 ?. That on such surfaces sulphur is always present.
 3. That native gold, or gold in pure state, readily absorbs sulphur from moist sulphur | eted hydrogen or sulphide of ammonium, and absorbs it directly when administered in boiling water.
 4. That surfaces so treated refuse to anal gamate, though no apparent change can be observed in their aspect.
 g. That gold so affected is rendered amalga- mable by roasting in an open fire, unless cop per is present to the extent of seven per cent. for perhaps less), while the same effect is produced by the contact of cyanide of potas- sium, chronic and nitric acid, and chloride of lime acidifed.
 G. That this absorption is altogether of a chemical nature.
 :. That sulphatcs of iron, in presence of air and water, decomposed various metallic sulphides common to auriferous reefs in such manner as to liberate sulphureted hydro gen.
 The action of sulphureted hydrogen upon gold, in rendering it non-amaigamabie when placed in contact with mercury, was demon strated with striking effect by the author be- fore the members of the society.
 From these results the author has been led to suppose that large area of the natural sur faces of native gold is covered with thin film of an auriterous sulphide, and that the greater part of the gold which escapes anal gamation at the battery is represented by that portion of this sulphurized gold which has remained unabraded during the processes of milling or extraction from the reef; the state of the gold, rather than that of the mercury, therefore, being the greatest imped- iment to thorough amagamation.
 In addition to these results, the author communicated others relative to the effect of solutions of sulphureted hydrogen and sul- phdie of ammonium upon platinum. In rcn- dering it non -amalgable, he believed . sul- phide of metal had formed in each case, since chronic acid rendered it again amalgamable. He also stated that this metal is also so af- fected by ammonia or the fixed alkalies that it will not amalgamate, except in presence of mineral acid, from which he suspects platina is capable of superficial oxidizement when in contact with alkaline substances, even at common temperatures. The author found that his samples of gold were not affected by the alkalies in this manner, except in case of one from Victoria, singularity from which was argued the presence of palladium in this particular sample.