dioxide lasts about thirty hours when the substances are mixed in the proportion of five parts carbon to four parts alumina. Morris states further that the metal appears as a porous spongy mass, and is freed from the residual alumina and particles of charcoal either by smelting it, technically "burning it out," with cryolite as a flux or by mechanical treatment.

REDUCTION BY CARBON.

About the first attempt of this nature we can find record of is the following article by M. Chapelle :-*

"When I heard of the experiments of Deville, I desired to repeat them, but having neither aluminium chloride nor sodium to use, I operated as follows: I put natural clay, pulverized and mixed with ground NaCl and charcoal, into an ordinary earthen crucible and heated it in a reverberatory furnace, with coke for fuel. I was not able to get a white heat. After cooling, the crucible was broken, and gave a dry pulverulent scoria in which were disseminated a considerable quantity of small globules about one-half a millimetre in diameter, and as white as silver. They were malleable, insoluble in nitric or cold hydrochloric acids, but at 60° dissolved rapidly in the latter with evolution of hydrogen; the solution was colorless and gave

* Compt. Rendus, 1854, vol. xxxviii, p. 358.

with ammonia a gelatinous precipitate of hydrated alumina. My numerous occupations do not permit me to assure myself of the purity of the metal. Moreover, the experiment was made under conditions which leave much to be desired, but my intention is to continue my experiments and especially to operate at a higher temperature. In addressing this note to the Academy I but desire to call the attention of chemists to a process which is very simple and susceptible of being improved. I hope before many days to be able to exhibit larger globules than those which my first experiment furnished."

M. Chapelle never did address any further communications to the Academy on this subject, and we must presume that further experiments did not confirm these first ones.

G. W. Reinar* states that the pyrophorous mass which results from igniting potash or soda alum with carbon, contains a carboniferous alloy of aluminium with potassium or sodium, from which the alkaline metal can be removed by weak nitric acid.

COWLES BROS.' PROCESS.

This process, which reduces alumina by carbon in the presence of another metal to take up the aluminium, using the electric furnace, is the nov

*Wagner's Jahresb. 1859, p. 4.

elty which is attracting widespread attention to the metallurgy of aluminium. Its history has already been sketched, and will be still further developed in the following pages. It properly comes under the heading of "Reduction by Carbon."

"Early in the present century, Sir H. Davy, Berzelius, and Oerstedt, all famous chemists, attempted unsuccessfully to reduce alumina by electricity. Likewise, many learned scientists have striven to decompose it by carbon, as other metals are smelted from their ores, but without success, and the opinion has become profound and widespread among chemists that alumina could not be reduced by carbon and heat. But this is exactly what the Cowles process accomplishes, and by its means the Cowles Electric Smelting and Aluminium Company is enabled to supply the alloys of aluminium with other metals at one-quarter to onethird their former price. As to the details of the process, we refer to the papers of Professor Hunt and the one read by Mr. Mabery."*

The following is the patent claim of Messrs. Cowles: U. S. Pat. 324,658 and 324,659, August 18, 1885. Electric smelting of aluminium. To Cowles Bros., Cleveland, Ohio. Claim: Reducing the aluminium compound in company with a metal in a furnace heated by electricity in presence of

* Cowles Bros.' Pamphlet.

carbon. The alloy of aluminium and the metal formed is treated to separate the aluminium.

The following paper is the first official and scientific account of Cowles Bros.' process, and was read before the American Association for the Advancement of Science by Professor Charles F. Mabery of the Case School of Applied Science, Cleveland.*

"The application of electricity to metallurgical processes has hitherto been confined to the reduction of metals from solution, while few attempts have been made to effect dry reductions by means of an electric current. Some time since Eugene H. Cowles and Alfred H. Cowles, of Cleveland, conceived the idea of obtaining a continuous high temperature on an extended scale by introducing into the path of an electric current some material that would afford the requisite resistance, thereby producing a corresponding increase in the temperature. After numerous experiments, coarsely pulverized carbon was selected as the best means for maintaining an invariable resistance, and at the same time as the most available substance for the reduction of oxides. When this material mixed with the oxide to be reduced was made a part of the electric circuit, enclosed in a fire-clay retort, and subjected to the action of a current from a powerful dynamo, not only was the oxide reduced,

* Ann Arbor Meeting, August 28, 1885.

but the temperature increased to such an extent that the whole interior of the retort fused completely. In other experiments lumps of lime, sand, and corundum were fused, with a reduction of the corresponding metal; on cooling, the lime formed large, well-defined crystals, the corundum beautiful red-green and blue octahedral crystals. Following up these results with the assistance of Prof. Mabery, who became interested at this stage, it was soon found that the intense heat thus produced could be utilized for the reduction of oxides in large quantities, and experiments were next tried on a large scale with the current from a fifty horse-power dynamo. For the protection of the walls of the furnace, which were of fire-brick, a mixture of ore and coarsely pulverized gas carbon was made a central core, and was surrounded on the side and bottom by fine charcoal, the current following the lesser resistance of the core from carbon electrodes inserted in the ends of the furnace in contact with the core. The furnace was charged by first filling it with charcoal, making a trough in the centre, and filling this with the ore mixture, the whole being covered with a layer of coarse charcoal. The furnace was closed on top with fire-brick slabs containing two or three holes for the escape of the gaseous products of the reduction, and the whole furnace was made air tight by luting with fire clay. Within a few minutes after starting the dynamo, a stream of carbonic oxide