290 STATE AND PROGRESS OF 
permeates every pore of the pulp. We have not seen this pan in 
operation, but it appears that the heat gained could not be 
sufficient to volatilise the mercury, except at a prohibitory 
expense. 
In chlorination there is not a single instance in which Plastner’s 
system is being employed, that known locally as the Newbery- 
Vautin process, with modifications, having entirely taken its 
place. We think some notice of this class of process is necessary, 
because there is some misconcepiion as to the origin of the 
principle. 
Dr. Mears seems to have been the first to introduce the 
system of working chlorination under pressure, and to do this he 
employed a revolving barrel, into which chlorine, generated 
from chloride of lime and sulphuric acid, was pumped, and the 
barrel was subsequently rotated. Mr. Thies evolved chlorine 
from the same substances, but did it in the barrel itself, not 
obtaining any adventitious pressure ; while Messrs. Newbery and 
Vautin proposed to secure the pressure by pumping in air, the 
chlorine being generated as in Mr. Theis’ process. The system 
employed here seems to be identical with that of Mr. Theis. 
In all chlorination it is necessary to keep the pulp damp after 
crushing, the test of suitability being that it can be crushed 
together in the hand, but commences to fall to pieces when the 
pressure is released. Under these conditions, the chlorine pene- 
trates the ore more completely than when it is dry, besides 
which, if allowed to dry it cakes, and has to be reground. 
SILVER ORES. 
The various processes of treating the more simple silver ores 
has been so thoroughly exhausted in numerous works on the 
subject that it would be going outside our province to note any 
details regarding it. For the free milling ores a chloridising 
roasting is first resorted to, and this is followed by amalgama- 
tion in pans. This process is now in operation at Waiorongomai, 
at Te Aroha, New Zealand, and will probably be introduced at 
the White Rock Mine in New South Wales. There have not, 
so far as we are aware, been any improvements introduced into 
the methods of treatment in these colonies, in which, indeed, the 
silver mining industry is but new. The principal method of 
treatment which has found favour here is by smelting, and this 
is adopted over a wide-spread area. At Broken Hill, Sunny 
Corner, Mount Costigan, Port Pirie, and other places the ores 
are smelted, and in some cases lead has been bought and passed 
through the furnaces with the view to recover the silver. In the 
majority of cases the water-jacket continuous furnaces are 
employed for smelting, and although, in some cases, refining has 
been attempted, the bullion is now generally shipped. At Sunny 
