1904-5. | THE CHEMICAL INDUSTRIES OF THE DOMINION. 159 
pheric temperatures, render it eminently suitable for replacing silver as a 
reflecting surface on optical instruments, for plating the finely cut scales 
on instruments of precision and for alloys. 
ALUMINUM. 
The extraction and refining of aluminum has in recent years, owing 
to the advent of electricity developed from cheap water power, become an 
important industry. At Shawinigan Falls, Quebec, are situated the 
Canadian works of the Northern Aluminium Company, a sub-company 
of the Pittsburgh Reduction Company, which also has two large factories 
at Niagara Falls, N.Y. ‘The raw material, bauxite, is obtained from Ala- 
bama, Arkansas and Georgia, in the United States. The process employed 
is the Hall!° process, and is a combined electrolytic and electric furnace one. 
The native aluminum hydroxide is first purified by mixing with sufficient 
carbon to reduce all impurities in it to the metallic state, the resulting iron, 
mixed with titanium and silicon, forming a slag after melting the mass in an 
electric furnace. An alternating current of low voltage is used, and the 
purified alumina separates out above the slag in an almost chemically 
pure condition. The alumina thus purified is then electrolyzed in a bath 
containing cryolite at a temperature of from 850° to goo® C. The action 
of the current sets free aluminum and oxygen, the latter uniting with the 
carbon anodes to form carbonic oxide. The metal is run into rough ingots 
weighing twenty pounds each, and is stated to contain, on an average, 
99.5 per cent. of aluminum.'© The principal portion of the product at 
Shawinigan is shipped in the form of ingots, although there is in addition 
a wire mill where aluminum wire and cable for electrical conductors are 
made. 
The production of the Quebec works is probably 9,500 pounds per 
day, the value in 1902 being approximately $1,043,250.!’ It may safely 
be said that the three works of-this company between them produce one- 
half of the world’s supply. 
LEAD AND SILVER. 
These metals are derived principally from the mines of British Colum- 
bia, but there are also deposits of galena along the shores of Lake Superior, 
the ore from which is sent to Niagara Falls, N.Y., for reduction. The 
British Columbia ore is a high grade one, carrying from 25 to 300 ounces 
of silver to the ton. At Trail, in British Columbia, the Canadian Smelt- 
(15) Dr. J. W. Richards in ‘‘ Electro-Chemical Industry,” Oct., 1902. 
(16) bid. (average value of product is 31 cents per pound). 
(17) Canadian Mining Rev., March, 1903. 
