Universal Exposition Paris, Volume 2

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Pagina 473 - ... that temperature, but undergoes incipient fusion at 730į. According to Faraday, aluminium ranks very high among metallic conductors of heat and electricity, and he found that it conducted heat better than either silver or copper. The specific heat is also very high, which accounts for length of time required for an ingot of the metal to either melt or get cold after being cast. Chemically, its properties are well worthy of study. Air, either wet or dry, has absolutely no effect on aluminium...
Pagina 460 - ... described. In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.
Pagina 455 - ... extraordinary care ; in fact, not so much as is required in working many other kinds of charges, the composition of the resulting steel being easily and definitely controlled.
Pagina 467 - ... an air-tight joint which prevents the escape of gas and vapour from the vessel during reduction, except by the hollow arm provided for this purpose. The natural expansion of the iron vessels is accommodated by the water-pressure in the hydraulic lifts, so that the joint of the cover and crucible are not disturbed until it is intended to lower the lift for the purpose of removing the crucible. The length of time required for the first operation of reduction and distillation is about two hours....
Pagina 467 - The successful working of this process marks an era in the production of sodium, as it not only has greatly cheapened the metal, but has enabled the manufacture to be carried out upon a very large scale with little or no danger. Practically, the process consists in heating fused caustic soda in contact with carbon whilst the former substance is in a perfectly liquid condition. By the process in vogue before the introduction of this method, it was always deemed necessary that...
Pagina 466 - ... of double chloride should be annually manufactured, but in addition that each of these materials should be produced at a very low cost, in order to enable the metal to be sold at 20 shillings per pound.
Pagina 470 - ... the metal thus obtained required to be refined. This was successfully accomplished by Mr. Castner and his able assistant, Mr. Cullen, and for some time all the metal made was refined, the iron being lowered to about 2 per cent. The process, however, was difficult to carry out, and required careful manipulation, but as it then seemed the only remedy for effectively removing the iron, it was adopted and carried on for some time quite successfully, until another invention of Mr. Castner rendered...
Pagina 469 - ... mains, &c., this being the only available metal which withstands the corrosive action of chlorine. The gasometers are filled in turn from the stills, the chlorine consumed being taken direct from a gasometer under a regular pressure until it is exhausted ; the valves being changed, the supply is taken from another holder, the emptied one being refilled from the still. Manufacture of the Double Chloride. Twelve large regenerative gas furnaces are used for heating, and in each of these are fixed...
Pagina 466 - Chemists of many lands have contributed to our knowledge of the metal aluminium. Davy, in 1807, tried in vain to reduce alumina by means of the electric current, Oerstedt, the Dane, in 1824, pointed out that the metal could be obtained by treating the chloride with an alkali metal; this was accomplished in Germany by...
Pagina 467 - The residue is cleaned out. and the hot pot being again gripped by the tongs is taken back to the furnace. On its way the charge of alkali and reducing material is thrown in. It is again placed on the lift and raised in position against the edges of the cover. The time consumed in making the change is...

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