During my investigations on the ore of the Deep Creek Mines, I have found in them what I believe to be gold existing as a natural sulphide.  The description of this ore will, no doubt, be of interest to your readers.

The lode is a large irregular one of pure arsenical pyrites, existing in a felsite dike near the sea coast.  Surrounding it on all sides are micaceous schists, and in the neighborhood is a large hill of granite about 800 ft. high.  In the lode and the rock immediately adjoining it are large quantities of pyrophylite, and in some places of the mine are deposits of this pure white, translucent mineral, but in the ore itself it is a yellow and pale olive green color, and is never absent from the pyrites.

From the first I was much struck with the exceedingly fine state of division in which the gold existed in the ore.  After roasting and very carefully grinding down in an agate mortar, I have never been able to get any pieces of gold exceeding the one-thousandth of an inch in diameter, and the greater quantity is very much finer than this.  Careful dissolving of the pyrites and gangue, so as to leave the gold intact, failed to find it in any larger diameter.  As this was a very unusual experience in investigations on many other kinds of pyrites, I was led further into the matter.  Ultimately, after a number of experiments, there was nothing left but to test for gold as a sulphide.

Taking 200 grammes of pyrites from a sample assaying 17 ounces fine gold per ton, grinding it finely, and; heating for some hours with a solution of sodium sulphide (Na_{2}S_{2}), on decomposing the filtrate and treating it for gold I got a result at the rate of 12 ounces gold per ton.  This was repeated several times with the same result.

This sample came from the lode at the 140 ft. level, while samples from the higher levels where the ore is more oxidized, although carrying the gold in the same degree of fineness, do not give as high a percentage of auric sulphide.

It would appear that all the gold in the pyrites (and I have never found any apart from it) has originally taken its place there as a sulphide.

The sulphide is an analysis of a general sample of the ore: 

Silica        13.940 p.c. 
Alumina        6.592  "
Lime           0.9025 "
Sulphur       16.584  "
Arsenic       33.267  "
Iron          27.720  "
Cobalt         0.964  "

                                 Per Ton. 
  Nickel Traces. 
  Gold 5 ozs. 3 dwts. 8 grs. 
  Silver 0 " 16 " 0 "
                -------
                99.969

Nambucca Head’s Gold Mining Company, Deep Creek, N.S.  Wales, Oct. 9, 1891.—­Chemical News.

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SOME MEANS OF PURIFYING WATER.