402 J. D. Whelpley on treatment of Gold and other metals, 
condition of thorough desulphurization was the reduction of the 
ores and sulphurets to an impalpable powder. The reason of this 
is evident; viz: that the effect of heat upon a particle increases 
inversely as the square of its diameter. 
Microscopic atoms are readily acted upon by combined air and 
moisture at acherry-red heat. Pieces of the size of mustard s 
will resist the action of the best managed furnace for hours, and 
the difficulty increases with the size of the particles directly as 
the squares of their diameters. 
A theoretically perfect process, therefore, requires :— 
1st, That every particle shall be microscopically small,—in 
the condition of fine, floating dust. 
2d, That the particles do not touch each other while hot. 
8d, That when metallic grains, as of gold or copper, have to 
be separated from the ore, the contact of water with the heated 
particles is necessary. 
We constructed a furnace in which finely pulverized ore-dust 
was floated in a current of hot air and flame, passing down 
through a flue leading from a hard-coal fire, at an angle of about 
45°, and then resting upon a horizontal hearth or sole.’ 
We discovered at this time that moisture or the vapor of water 
in large quantities materially aided the process of desulphuriza- 
tion in free air, and we constructed and applied a steam appa 
ratus by which a volume of steam was made to pass down the 
inclined flue with the ore-dust, the atmosphere, and the products 
of combustion. : 
At this point we encountered several serious difficulties. The 
inside of the inclined flue became lined with stalactoid masses of 
semi-fused ores, and the sole of the furnace caked and covered 
with the same. When a certain quantity of burnt ore had ac- 
cumulated on the hearth, a trap was opened and the heated mass 
pushed through into a water-bath. The agglutinated masses 
on being withdrawn from the bath, were re-ground, and passed 
a second time through the furnace. 
A sufficiency of atmospheric air could not be applied throu 
the furnace doors, and a very large percentage of the ores & 
eaped through the chimney into the open air. 
he last of these difficulties was overcome by placing a power 
ful fan wheel of copper (which served also as a water or Spray 
wheel) in the chimney itself, or in a chamber of it, and by cP 
rying the horizontal flue some 75 feet beyond this wheel. |. 
The steam from the furnace and the spray from this wheel, 
working over a pool of water which formed the floor of a of 
zontal flue, effectually wetted down and saved the flying dust 
ore, 
> This furnace was built and worked in Charlestown, (Mass.) in May, Ju0® ol 
July, 1861.—3, v. w. 
