190 
ELECTROMETALLURGY.—ALUMINIUM. 
From 3 to 1 % aluminium added to the above alloy constitutes aluminium 
brass, the hardness of the new alloy varying directly with the amount of aluminium. 
Here are the usual proportions :— 
Copper. Zinc. Aluminium. 
No. 1.................. 71-25 25 3*75 
„ 2... 63*33 33-33 3‘33 
Silicon bronzes contain from 14 to 6 °/ Q of silicon. This material is used for 
copper wires for electrical conductors. Ferro-aluminium has from 30 to 10 °/ 0 
of aluminium. It is employed in steel metallurgy, especially for the production 
of flawless cast-steel. 
HEROULT-KILIANI PROCESS. 
M. Heroult’s patent in 1886 contemplated the direct decomposition of alumina 
by the electric current. It was applied in 1888 at the Swiss works of Neuhausen, 
belonging now to the “ Aluminium Industrie Actien- Gesellschaft ,’’ the pro¬ 
prietors of the foreign patents. These works are the largest aluminium works in 
existence. They are situated on the Rhine, near the celebrated Fall, and the 
Canton of Schaffhausen, has conceded to the Company a volume of water equal 
to 20 cubic metres a second (about 440 gallons); the fall being 20 metres, the 
net motive-power is about 5000 horse-power. The old horizontal water-wheels 
have been recently replaced by a group of three Jonval vertical ones, two of 
600 horse-power and 43 inches mean diameter, and one of 300 with diameter of 
28 inches. Two large Brown dynamos from the works at Oerlikon, of 200 
nominal kilowatts with a speed of 200 revolutions per minute, are -worked by the 
principal water-wheels. These machines have given as much as 402 kilowatts, 
with a current of 14,000 amperes at 30 volts. The third water-wheel at Neu¬ 
hausen actuates a dynamo which discharges a current of 3000 amperes at 65 volts, 
and a speed of 300 revolution's. So that, counting an old dynamo kept in reserve, 
Neuhausen disposes of a total energy which may reach the figure of 1500 kilo¬ 
watts. 
Originally the Heroult furnace consisted of a graphite crucible heated in an 
ordinary crucible oven for melting alumina added to cryolite. The kathode was 
formed of a small crucible of conducting carbon placed within the first, and the 
positive by a carbon pencil immersed in the bath. 
Afterwards the system was simplified by M. Heroult and the interior crucible 
abolished. It was soon discovered that the heating of the furnace was useless ; 
the arc, started by the granulated copper, fused the mass, and the action of the 
apparatus was secured without any ancillary heat. 
In 1887-M. Heroult again modified his furnace, and made his carbon crucible from 
the negative electrode, with a covering of fire clay, through which passed a posi¬ 
tive carbon electrode. Copper, which was the first part of the charge introduced, 
was fused by the current, and this metallic bath was the kathode, the alumina 
and cryolite were then decomposed, the oxygen combined with the carbon of the 
anode, and carbonic oxide escaped through the holes of the covering clay, while 
the nascent aluminium allied itself to the molten copper; the cryolite gave 
fluidity to the bath, which was fed with rich alumina and copper. But with all 
this it was impossible to obtain pure aluminium. When the copper was with¬ 
drawn, the addition of alumina alone soon made the bath of a clammy consistency, 
and pure aluminium was as far off as ever. 
There is therefore much analogy between the systems of Cowles and Heroult. 
There is however this difference : Cowles system is simply calorific, Heroult’s 
is in addition electrolytic. 
Mr. Kiliani, the manager of the works at Neuhausen, discontinued in 1889 the 
use of copper at the kathode to start the arc. He observed that the active region 
