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should not be more than four hours. When the gas can be applied in a previously heated condition as well as being strongly compressed, the reduction. takes place in a still shorter period.

Nothing is now heard of this process, and it has been presumably a failure. It is said that several thousand dollars were expended by Mr. Fleury and his associates without making a practical success of it. We should be glad to hear in the future that their sacrifices have not been in vain, and that the process still has possibilities in it which will some time be realized.

Petitjean* makes aluminium sulphide, Al3S3, by one of Fremy's methods,t or makes a double sulphide of aluminium with potassium or sodium by mixing alumina with a little tar or turpentine in a carbon lined crucible, heating strongly, and then mixing with a powder composed of Na2CO3, or K2CO3, and sulphur; again heating a long time at bright redness. The sulphide or double sulphide thus made is put in a crucible or retort through the bottom of which can be led a stream of carburetted hydrogen, which separates the aluminium from its combination with the sulphur. Aluminium‡ can also be reduced from A12S3 by mixing it with iron filings or a pulverized metal having

* Kerl and Stohman, Poly. Central Blatt. 1858, 888.
+ See Appendix.

See Appendix.

similar qualities, and melting the mixture. A metallic mixture may be used instead of carburetted hydrogen in the above operation.

REDUCTION BY DOUBLE REACTION.

M. Comenge,* of Paris, obtains aluminium from its sulphide either by heating it in an atmosphere of hydrogen, or by heating it with Al2O3 or Al2(SO4)3 in such proportions that sulphur dioxide, SO2, and aluminium may be the sole products; or the sulphide may be decomposed by iron, copper, or zinc. The reactions involved would beA12S3+3H-H=2A1+ 3H2S. A12S3+2A1203=6A1+3S02. A12S3+A12(SO13=4A1+6SO2.

A21S3+3(Fe.Cu.Zn.)=2A1+3(Fe.Cu.Zn.)S.

Johnsont patented the following process: Aluminium sulphide is mixed with quite dry Al2(SO4)3 in such proportions that the sulphur and oxygen present may evolve as SO2. The mixture is heated to redness in an unoxidizing atmosphere, when SO2 evolves and the metal remains. The reaction is furthered by agitation. The aluminium in the resulting mass can be treated in the way commonly used in puddling spongy iron, and then either pressed or hammered together. Or, the aluminium

* Eng. Pat. 1858, No. 461.

Kerl and Stohman's Handbuch.

sulphide may be heated to redness in an unoxidizing atmosphere and dry hydrogen or water gas conducted over it, and the metal separated from the resulting mass by dressing.

Mr. Niewerth's* process may be operated in his newly invented furnace, but it may also be carried on in a crucible or another form of furnace. The furnace alluded to consists of three shaft furnaces, the outer ones well closed on top by iron covers, and connected beneath by tubes with the bottom of the middle one: the tubes being provided with closing valves. These side shafts are simply watergas furnaces, delivering hot water-gas to the central shaft, and by working the two alternately supplying it with a continuous blast. The two producers are first blown very hot by running a blast of air through them with their tops open, then the cover of one is closed, the blast shut off, steam turned on just under the cover, and water gas immediately passes from the tube at the bottom of the furnace into the central shaft. The middle shaft has meanwhile been filled with these three mixtures in their proper order:

First. A mixture of sodium carbonate, carbon, sulphur, and alumina.

Second. Aluminium sulphate.

Third. A flux, preferably a mixture of NaCl and KCI.

*Sci. Am. Suppl., Nov. 17, 1885.

This central shaft must be already strongly heated to commence the operation, it is best to fill it with coke before charging, and as soon as that is hot to put the charges in on the coke. Coke may also be mixed with the charges, but it is not necessary. The process then continues as follows: The water-gas enters the bottom of the shaft at a very high temperature. These highly heated gases, carbonic oxide and hydrogen, act upon the charges so that the first breaks up into a combination of sodium sulphide and aluminium sulphide, from which, by means of the second charge of Al2(SO4), free aluminium is reduced. As the latter passes down the shaft, it is melted and the flux assists in collecting it, but is not absolutely necessary. Instead of producing this double sulphide, pure aluminium sulphide might be used for the first charge, or a mixture which would generate A1253; or, again, pure Na2S, K2S, CuS, or any other metallic, sulphide which will produce the effect alone, in which case aluminium is obtained alloyed with the metal of the sulphide. Instead of the first charge a mixture of alumina, sulphur, and carbon might be introduced. Or, the Al2(SO4)3 of the second charge might be replaced by alumina. So, one charge may be Na2S, K2S, or any other metallic sulphide, and the second charge may be either Al2O3 or Al2(SO1)3.

REDUCTION BY CARBON AND CARBON DIOXIDE.

J. Morris* of Uddington claims to obtain aluminium by treating an intimate mixture of alumina and charcoal with carbon dioxide. For this purpose, a solution of AlCl is mixed with powdered wood-charcoal or lampblack, then evaporated till it forms a viscous mass which is shaped into balls. During the evaporation hydrochloric acid is given off. The residue consists of alumina intimately mixed with carbon. The balls are dried, then treated with steam in appropriate vessels for the purpose of driving off all the chlorine, care being taken to keep the temperature so high that the steam is not condensed. The temperature is then raised so that the tubes are at a low red heat, and dry carbon dioxide,CO2, is then passed through. This CO2 is said to be reduced by the carbon to carbonic oxide, CO, which now, as affirmed by Mr. Morris, reduces the alumina. Although the quantity of carbonic oxide escaping is in general a good indication of the progress of the reduction, it is, nevertheless, not advisable to continue heating the tubes or vessels until the evolution of this gas has ceased, as in consequence of slight differences in the consistency of the balls some of them give up all their carbon sooner than others. The treatment with carbon

* Dingler, 1883, vol. 259, p. 86. German Pat. No. 22150, Aug. 30, 1882.

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