ALUMINA.

Blue-black shale, Pine Brook drift 27.36

Slate from Briggs' Shaft coal 15.93

Black fire clay, 4 ft. thick, Nos. 4 and 5 Rolling Mill mines 23.53

First cut on railroad, black clay above Rolling Mill 32.60

G vein black clay, Hyde Park mines 28.67

It will be seen that the black clay, shale, or slate, has a constituent

of aluminum of from 15.93 per cent., the lowest, to 32.60 per cent., the

highest. Under every stratum of coal, and frequently mixed with it, are

these under deposits that are rich in the metal. When exposed to the

atmosphere, these shales yield a small deposit of alum. In the

manufacture of alum near Glasgow the shale and slate clay from the old

coal pits constitute the material used, and in France alum is

manufactured directly from the clay.

Sufficient has been advanced to warrant the additional assertion that we

are here everywhere surrounded by this incomparable mineral, that it is

brought to the surface from its deposits deep in the earth by the

natural process in mining, and is only exceeded in quantity by the coal

itself. Taking a columnar section of our coal field, and computing the

thickness of each shale stratum, we have from twenty-five to sixty feet

in thickness of this metal-bearing substance, which averages over

twenty-five per cent. of the whole in quantity in metal.

It is readily apparent that the only task now before us is the reduction

of the ore and the extraction of the metal. Can this be done? We answer,

it has been done. The egg has stood on end--the new world has been

sighted. All that now remains is to repeat the operation and extend the

process. Cheap aluminum will revolutionize industry, travel, comfort,

and indulgence, transforming the present into an even greater

civilization. Let us see.

We have seen the discovery of the mere chemical existence of the metal,

we have stood by the birth of the first white globule or bead by Wohler,

in 1846, and witnesssed its introduction as a manufactured product in

1855, since which time, by the alteration and cheapening of one process

after another, it has fallen in price from thirty-two dollars per pound

in 1855 to fifteen dollars per pound in 1885. Thirty years of persistent

labor at smelting have increased the quantity over a thousandfold and

reduced the cost upward of fifty per cent.

All these processes involve the application of heat--a mere question of

the appliances. The electric currents of Berzelius and Oersted, the

crucible of Wohler, the closed furnaces and the hydrogen gas of the

French manufacturers and the Bessemer converter apparatus of Thompson,

all indicate one direction. This metal can be made to abandon its bed in

the earth and the rock at the will of man. During the past year, the

Messrs. Cowles, of Cleveland, by their electric smelting process, claim

to have made it possible to reduce the price of the metal to below four

dollars per pound; and there is now erecting at Lockport, New York, a

plant involving one million of capital for the purpose.

Turning from the employment of the expensive reducing agents to the

simple and sole application of heat, we are unwilling to believe that we

do not here possess in eminence both the mineral and the medium of its

reduction. Whether the electric or the reverberatory or the converter

furnace system be employed, it is surely possible to produce the result.

To enter into consideration of the details of these constructions would

involve more time than is permitted us on this occasion. They are very

interesting. We come again naturally to the limitless consideration of

powdered fuel, concerning which certain conclusions have been reached.

In the dissociation of water into its hydrogen and oxygen, with the

mingled carbon in a powdered state, we undoubtedly possess the elements

of combustion that are unexcelled on earth, a heat-producing combination

that in both activity and power leaves little to be desired this side of

the production of the electric force and heat directly from the carbon

without the intermediary of boilers, engines, dynamos, and furnaces.

In the hope of stimulating thought to this infinite question of proper

fuel combustion, with its attendant possibilities for man's

gratification and ambition, this advanced step is presented. The

discussion of processes will require an amount of time which I hope this

Board will not grudgingly devote to the subject, but which is impossible

at present. Do not forget that there is no single spot on the face of

the globe where nature has lavished more freely her choicest gifts. Let

us be active in the pursuit of the treasure and grateful for the

distinguished consideration.

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Scientific American Supplement, No. 531, March 6, 1886 · 第 37 / 54 题