Sprague* also states his inability to deposit aluminium electrically from solution. M. L. Senett electrolyzes a saturated solution of Al2(SO4)3, separated by a porous septum from a solution of NaCl. A current is used of four ampères. The double chloride, Al2C16.2NaCl, is formed, then decomposed, and the aluminium liberated deposited on the negative electrode.. Gerhard and Smith patented a process for depositing electrically aluminium and its alloys. John Braung decomposes a solution of alum, of specific gravity 1.03 to 1.07, at the usual temperature, using an insoluble anode. In the course of the operation, the sulphuric acid set free is neutralized by the continual addition of alkali; and, afterwards, to avoid the precipitation of alumina, a non-volatile organic acid is added to the solution. Moses G. Farmer has patented an apparatus for obtaining aluminium electrically consisting of a series of conducting cells in the form of ladles, each ladle having a handle of conducting material extending upwards above the bowl of the next succeeding ladle; each ladle can be heated separately from the rest; the anodes are hung in the ladles, being suspended from the handles of the *Sprague's Electricity, p. 309. Cosmos les Mondes, Aug. 10, 1885. § German Pat., No. 28,760. || U. S. Pat., No. 315,266, Apr. 1885. preceding ladles, the ladles themselves being the cathodes. Mierzinski says that the deposition of aluminium from an aqueous solution of its salt has not yet been accomplished, and declares Gore to have been in error when he stated that he had covered copper with a film of aluminium by using a feeble current and a solution of Al2C16 in water. Several years ago, the writer was in Mr. Frishmuth's works, in Philadelphia, and observed that he was then doing a large amount of plating, depositing an alloy of aluminium and nickel. Nickel plating is known to be very hard and lasting, but it has a dark-bluish color, not agreeable to many. The presence of aluminium with it whitens it so that the plating is a very close imitation of silver, and wears much better than silver plating. He was depositing with a twenty horse-power dynamo. The articles were previously cleaned in a hot potash solution, and then hung in the plating bath. I do not know the composition of his solution, he keeps that secret, but it was green and strongly ammoniacal. PART XI. WORKING IN ALUMINIUM. MELTING ALUMINIUM. DEVILLE: To melt aluminium it is necessary to use an ordinary earthen crucible and no flux. Fluxes are always useless and almost always harmful. The extraordinary chemical properties of the metal are the cause of this; it attacks very actively borax or glass with which one might cover it to prevent its oxidation. Fortunately this oxidation does not take place even at a high temperature. When its surface has been skimmed of all impurities it does not tarnish. Aluminium is very slow to melt, not only because its specific heat is considerable, but its latent heat appears very large. It is best to make a small fire and then wait patiently till it melts. One can very well work with an uncovered crucible. When it is desired to melt pieces together, they can be united by agitating the crucible or compressing the mass with a well-cleaned, cylindrical bar of iron. Clippings, filings, etc., are melted thus: Separate out first, as far as possible, foreign metals, and to avoid their combining with the aluminium heat the divided metal to as low a heat as possible, just sufficient to melt it. The oil and organic matters will burn, leaving a cinder, which hinders the reunion of the metal if one does not press firmly with the iron bar. The metal may then be cast very easily, and there is found at the bottom of the crucible a little cinder which still contains a quantity of aluminium in globules. These may be easily separated by rubbing in a mortar and then passing through a sieve, which retains the flattened globules. Kerl & Stohman: To be able to melt well and pour aluminium, the whole quantity of metal which is to be melted at one time must not be put into the crucible at once, but little by little, so increasing the mass from time to time as the contents become fully melted. The necessary knack for attaining a good clean melt consists in dipping the pieces which are to be melted together in benzine before putting in the crucible. Mourey even pours a small quantity of benzine into the crucible after the full melting of the metal, and he recommends the employment of benzine in the melting of all the noble metals. Turning to the cases arising in the employment of aluminium in the different industrial arts, one must as far as possible separate out first the pieces which have been soldered, in order that the newly melted aluminium may not be contaminated by the solder. The solder adhering to these pieces can be removed by treating them with nitric acid, by which the aluminium is not attacked. Mierzinski: To melt aluminium one cannot heat it in common clay crucibles, because it reduces silicon from them, by which the metal becomes gray and brittle. This difficulty can be removed by lining the crucible with carbon, or better, with wellburnt cryolite-clay. Moreover, in practice, it is only in the rarest cases that pure aluminium is obtained to be melted up, but, as a rule, it is alloyed with four to eight per cent. of silver. CASTING ALUMINIUM. Deville: Aluminium can be cast very easily in metallic moulds, but better in sand for complicated objects. The mould ought to be very dry, made of a porous sand, and should allow free exit to the air expelled by the metal, which is viscous when melted. The number of vents ought to be very large, and a long, perfectly round git should be provided. The aluminium, heated to redness, ought to be poured rather quickly, letting a little melted metal remain in the git till it is full, to provide for the contraction of the metal as it solidifies. In general, this precaution ought to be taken even when aluminium is cast in iron ingot moulds or moulds of any other metal. The closed ingot moulds give the best metal for rolling or hammering. By following these precautions, castings of |