to imitate as closely as possible the organic matter supposed to decompose the solution circulating through the drifts, I first immersed a piece of cubic iron pyrites taken from the coal formation of Cape Otway, far distant from any of our gold rocks, and therefore less likely to contain gold than other pyrites.  The specimen (No. 1) was kept in dilute solution for about three weeks, and is completely covered with a bright film of gold.  I afterwards filed off the gold from one side of a cube crystal to show the pyrites itself and the thickness of the surrounding coating, which is thicker than ordinary notepaper.  If the conditions had continued favourable for a very lengthened period, this specimen would doubtless have formed the nucleus of a large nugget.  Iron, copper, and arsenical pyrites, antimony, galena, molybdenite, zinc blende, and wolfram were treated in the above manner with similar results.  In the above experiments a small chip of wood was employed as the decomposing agent.  In one instance I used a piece of leather.  All through the wood and leather gold was disseminated in fine particles, and when cut through the characteristic metallic lustre was brightly reflected.  The first six of these sulphides were also operated upon simply in the solution without organic matter; but they remained unaltered.”

Wilkinson found that when the solution of gold chloride was as strong as, say, four grains to the ounce of water, that the pyrites or other base began to decompose, and the iron sulphide changed to yellow oxide, the “gossan” of our lodes, and that though the gold was deposited, this occurred in an irregular way, and it was coated with a dark brown powdery film something like the “black gold,” often found in drifts containing much ferruginous matter.  Such were the curious Victorian nuggets Spondulix and Lothair.

Professor Newbery also made a number of similar experiments, and arrived at like results.  He states as follows:  “I placed a cube of galena in a solution of chloride of gold, with free access of air, and put in organic matter; gold was deposited as usual, in a bright metallic film, apparently completely coating the cube.  After a few months the film burst along the edges of the cube, and remained in that state with the cracks open without any further alteration in size or form being apparent.  Upon removing it a few days ago and breaking it open, I found that a large portion of the galena had been decomposed, forming chloride and sulphate of lead and free sulphur, which were mixed together, encasing a small nucleus of undecomposed sulphate of lead.  The formation of these salts had exerted sufficient force to burst open the gold coating, which upon the outside had the mammillary form noticed by Wilkinson, while the inside was rough and irregular with crystals forcing their way into the lead salts.  Had this action continued undisturbed, the result would have been a nugget with a nucleus of lead salts, or if there had been a current to remove the results of decomposition, a nugget without a nucleus of foreign matter.”