ease. issued through the openings, burning usually with a flame eighteen inches high. The time required for complete reduction was ordinarily about an hour. Experience has already shown that aluminium, silicon, boron, manganese, sodium, and potassium can be reduced from their oxides with In fact, there is no oxide that can withstand the temperature attainable in this furnace. Charcoal is changed to graphite; does this indicate fusion? As to what can be accomplished by converting enormous electrical energy into heat within narrow limits it can only be said that it opens the way into an extensive field of pure and applied chemistry. It is not difficult to conceive of temperature limited only by the power of carbon to resist fusion. "Since the motive power is the chief expense in accomplishing reductions by this method, its commercial success is closely connected with obtaining power cheaply. Realizing the importance of this point,, Messrs. Cowles have purchased at Lockport, N. Y., a water-power where they can utilize 1200 horse-power. An important feature in the use of these furnaces from a commercial standpoint is the slight technical skill required in their manipulation. The four furnaces operated in the experimental laboratory at Cleveland are in charge of two young men, who six months ago knew absolutely nothing of electricity. The products at present manufactured are the various grades of aluminium bronze, made from a rich furnace product obtained by adding copper to the charge of ore. Aluminium silver is also made; and a boron bronze may be prepared by the reduction of boracic acid in contact with copper, while silicon bronze is made by reducing silica in contact with copper. As conimercial results may be mentioned the production in the experimental laboratory, which averages 50 pounds of 10 per cent. aluminium bronze daily, which can be supplied to the trade in large quantities on the basis of $5 per pound for the aluminium contained, the lowest market quotation of aluminium being now $15 per pound.” Dr. T. Sterry Hunt has written and read several papers on this furnace and process, and we extract from them anything not mentioned in Prof. Mabery's paper. The following paper was read before the Am. Ins. of Mining Engineers by Dr. T. Sterry Hunt, of Montreal:-* "The application of electricity in the extraction of metals has hitherto been chiefly confined to the electrolysis of dissolved or fused compounds by various methods. The power of electric currents to generate intense heat in their passage through a resisting medium has long been known, and the late Sir Wm. Siemens thereby succeeded in melting * Halifax Meeting, Sept. 16, 1885. considerable quantities of steel. Messrs. Cowles took a new step in the metallurgic art by making the heat thus produced a means of reducing, in presence of carbon, the oxides not only of the alkali metals, but of calcium, magnesium, manganese, aluminium, silicon, and boron, with an ease which permits the production of these elements and their alloys with copper and other metals on a commercial scale. "If alumina, in the form of granular corundum, is mixed with the carbon in the electric path, aluminium is rapidly liberated, being in part carried off with the escaping gas and in part condensed in the upper layer of charcoal. In this way are obtained considerable masses of nearly pure aluminium, and others of a crystalline compound of the metal with carbon. When, however, some granular copper is placed with the corundum, an alloy of aluminium and copper is obtained, which is probably formed in the overlying stratum, but at the close of the operation is found in fused masses below. In this way there is obtained, after the current has passed an hour and a half through the furnace, four or five pounds of an alloy containing 15 to 20 per cent. of aluminium and free from iron. On substituting this alloy for the copper in a second operation, an alloy with over 30 per cent. aluminium is obtained. The difficulties in the way of gathering together the reduced metal without the aid of copper promise to be overcome at an early day, so that we may expect a cheap production of such alloys and of the pure metal. The present plant at Cleveland is but an experimental one, and has been in operation only a few months. The company will soon put in operation at Lockport a 125 horse-power dynamo, and nine more of equal power will be added, permitting the establishment of the electric furnace on a large scale." Paper read before the National Academy of Science by Dr. Hunt:-* "Dr. Hunt showed some alloys of aluminium with carbon and silicon, and a peculiar alloy believed to consist entirely of aluminium and nitrogen. As yet, the pure metal has only been. produced direct from the furnace in small lumps, but it may be obtained by melting an alloy of aluminium and tin with lead, when the latter takes up the tin and separates from the aluminium, sinking beneath it. Or, we get aluminium by subliming either its alloy with carbon or with copper, when the pure aluminium is carried over. The maximum amount of aluminium which copper can tolerate is 10 per cent., until we approach the other end of the scale, when alloys with 70 to 80 per cent. of aluminium, or more, give valuable workable alloys. In the early experiments with the Cowles furnace, an engine of 30 horse-power running a dynamo yielded a daily output of 50 pounds of *Washington Meeting, April 30, 1886. 10 per cent. aluminium bronze. Brush has now constructed an engine running 900 revolutions per minute, which for every 35 horse-power developed reduces one pound of the alloy per hour. The expense of working is now covered by one-half cent per horse-power per hour; thus the cost of the alloy is about 17 cents per pound. Within the past week, the gases given off by the furnace have been analyzed. In the first part of the process it is found that a large amount of nitrogen is given off, showing that air leaks into the furnace. After an hour and a half this gas is much diminished. The Cowles at first used moist carbon for packing, but have now overcome the necessity of dampening it, thereby saving the waste of heat in driving out the water." The latest and most complete description of the process is a paper read by Mr. W. P. Thompson before the Liverpool Section of the Society of Chemical Industry.* Mr. Thompson has been Cowles Bros.' agent in taking out their patents in England. The paper is as follows:— "That this invention is a new departure will be acknowledged by every one when they learn that chromium, titanium, silicon, aluminium, calcium, and the other alkaline earth metals are obtained by direct reduction of their oxides by carbon—till * Jrnl. of the Soc. of Chem. Industry, April 29, 1886. |