188 
ELECTRO-METALLURGY.—ALUMINIUM. 
electrode, the other to the negative; the moveable connection consists of a 5- 
strand cable, each strand of 13 copper wires of '28" diameter. 
The Cowles furnace is as represented in Figs. 1 and 2. To charge it the 
electrodes are first fixed at their maximum distance apart, and the hearth is pre¬ 
pared. Charcoal dust, pulverised in a mill, and afterwards mixed with lime-wash 
and dried in a stove, is then rammed down to a thickness of six or eight inches. 
This preparation prevents the charcoal from too rapidly turning into graphite 
under the action of the current and becoming a conductor. An iron mould, to 
make a cavity for the charge, is then placed in the centre and surrounded at a 
Fig-. 1.—Cowles Furnace. 
Longitudinal Section and Elevation. 
Fig. 2.—Cowles Furnace. 
Transverse Section. 
distance of about a quarter-of-an-inch with the same mixture of charcoal and 
lime. The mould is then carefully withdrawn, and the electrodes introduced at a 
minimum distance from one another of about a quarter-of-an-inch, and the 
charge is placed in the furnace. 
For aluminium bronze the charge consists of:— 
Corundum or emery. 2 
Copper in bars ... 4 
Pulverised wood charcoal. 1 
The bars of copper are placed transversely to the electrodes; they have been 
substituted for granulated copper, which by its too rapid fusion formed a short 
circuit. The mass of the charge is covered with desiccated sawdust, a bad con- 
