then set revolving at about ten revolutions a minute, the power being transmitted by a friction wheel.  According to the nature of the ore, or the size of the grains of gold, this movement is continued from one to four hours, during which time the gold, from combination with the chlorine gas, has formed a soluble gold chloride, which has all been taken up by the water in the barrel.  The chlorinator is then stopped, and the gas and compressed air allowed to escape from the valve through a rubber hose into a vat of lime water.  This is to prevent the inhalation of any chlorine gas by the workmen.  The manhole cover is now removed and the barrel again set revolving, by which means the contents are thrown automatically into the filter below.  This filter is an iron vat lined with lead.  It has a false bottom, to which is connected a pipe from a vacuum pump working intermittently.  As soon as all the ore has fallen from the chlorinator into the filter, the pump is set going, a partial vacuum is produced in the chamber below the false bottom in the filter, and very rapid filtration results.  By this means all the gold chlorides contained in the wet ore may be washed out, a continual stream being passed through it while filtration is going on.  The solution running from the filter is continually tested, and when found free from gold, the stream of water is stopped, as is also the vacuum pump.  The filter is then tipped up into a truck below, and the tailings run out to the waste heap.  The process of washing and filtration occupies about an hour, during which time another charge may be in process of treatment in the chlorinator above.  The discharge from the filter and the washings are run into a vat, and from this they are allowed to pass slowly through a tap into a charcoal filter.  During the passage of the liquid through the charcoal filter, the chloride of gold is decomposed and the gold is deposited on the charcoal, which, when fully charged, is burnt, the ashes are fused with borax in a crucible, and the gold is obtained.

[Illustration:  THE NEWBERY-VAUTIN CHLORINATION PROCESS.]

We have specified above the objections to the old processes of chlorination, so it may be fairly asked in what way the Newbery-Vautin process avoids the various chemical actions which have hitherto proved so difficult to contend with.

For any system of chlorination yet introduced it is necessary to free the ore from sulphides.  This is done by roasting according to any of the well-known systems in vogue.  It is a matter which requires great care and considerable skill.  The heat must be applied and increased slowly and steadily.  If, through any neglect on the part of the roaster, the ore is allowed to fuse, in most cases it is best to throw the charge away, as waste.  This roasting applies equally to the Vautin process as to any others.  So on this head there is no alteration.  One of the most important advantages is not a chemical one,