374 Transactions.— Chemistry. 
2nd. The same experiment repeated, but vessel and contents not darkened. 
Same results as before. 
3rd. Gold solution reduced to half its strength, and time of total deposition 
extended to four months. Diffused sunlight admitted. 
4th. Soluble organic matter used in place of wood ; sunlight excluded. 
Time of total deposition of gold two months. 
No discernible difference in results upon point in question to those 
obtained in experiment No. 1 
So far, therefore, as is shown by these results gold reduced from solution 
of its chloride by aid of such kinds of organic matter as cork or wood, 
does not in the manner of its deposition exhibit such a notable selective power 
for metallic gold as the description -of Mr. Daintree’s results would lead us to 
suppose. It does not, indeed, show any such selective process at all, that is 
to a greater extent than can be attributed to the action of surfaces generally 
regardless of their nature ; and in support of this, I believe I am correct in 
stating that the whole sum of our experiences (omitting those of Mr. Daintree) 
is directly against this theory, as to the rapid and marked deposition of gold 
on gold in the manner stated ; indeed, so far as I am aware, we only produce 
by these means fine incoherent powder—minute crystals or films of exceeding 
thinness—nothing nuggetty. We get a certain size of grain or crystal or a 
certain thickness of film, which our efforts have hitherto failed to enlarge. 
Our experience therefore on this point being in such opposition to that 
of Mr. Daintree quoted above, and which he quiescently allows to be 
imputed to him, and the subject itself being a most important one, it does 
seem that the data upon which these apposite statements are founded should 
be ample, of a definite character, and clearly stated ; but so far it does not 
appear by any means certain, from all I am able to gather on the subject, 
whether there was in reality any notable deposition of gold on the undissolved 
residue of gold, and if so, whether the reduction of this gold was solely effected 
by agency of organic matter. Thus Mr. Wilkinson states, “‘ Accidentally some 
extraneous substance, Supposed to be a piece of cork, had fallen into the 
solution, decomposing and precipitating the gold.” Here then we are led to 
suppose that the vessel containing the solution, ete., was not closed. What, 
therefore, might not be reasonably supposed to have fallen in besides cork, or 
any other kind of organic matter? Pyritous dust, or even a small nugget of this 
substance, might have accidentally fallen in this solution, splintered off from 
some specimen which perchance Mr. Daintree himself might have ben 
examining ; pyritous matters generally being able, as I have shown, to 
reduce gold from such solutions, and to deposit it indefinitely upon gold or 
other electric conductor. Unless precautions had been taken, therefore, to 
prevent the introduction of reducing agents other than those coming under 
