decompose oxides. At one of the poles of his battery he had a globule of mercury, having a very correct idea that this would amalgamate as we now call it, so that an amalgam or “alloy” of mercury and of the metal would be produced by the current, and the mercury would act as a sort of collector of metal. It was by processes such as this that Davy produced sodium and potassium, but he could not produce unalloyed aluminium. That metal evaded him, but he did get alloys of it, or at least an alloy. Sir Humphrey Davy’s work in those days, excited the greatest public interest, comparable to that which the theorizing of Einstein and the work of such men as Millikan and Compton and of the investigators of the General Electric Company in Schenectady occasion now. For his operations he needed a powerful electric battery, and the primary batteries of those days were the only source they had for generating electric power of any considerable amount. A great number of jars were required for real power, and it was a long and tedious affair to set them up and fill them with solutions. From the moment the solution entered them, the zinc plates began to deteriorate, the copper or other negative plate would begin to polarize, as it is called, so that to get anything like power, even as much as every automobile uses in its starting, a very large battery would be required, and to get the good out of it there should not have been the least delay in starting work with it, because of this automatic and rapid deterioration in power.
To express appreciation for the work done by Sir Humphrey Davy with the battery, which included the production of the electric arc, we are told that the present of a great battery was made to Davy. But he had not yet obtained pure aluminium.
THIS was produced some ten years after his time—first as a gray powder and then as little pellets. The French chemist, Sainte-Claire Deville, followed up the work of preceding investigators and by using sodium as the reducing agent, where the far more expensive potassium formerly had been employed, approached what might be called, a manufacturing process. Deville’s experiments led to the establishment of a metallurgical plant in France under the auspices of Napoleon the Third, who was then Emperor.
The metal was exhibited at the different World’s Fairs and used to be called the “silver of clay.” It was quite the thing to give a piece of aluminium to someone to hold, so that they would realize its lightness, about a third that of iron, and great astonishment was excited by this feature. When first exhibited at a World’s Fair in 1855, it was very expensive. A pound of it was worth $90.00. This is not far from one-quarter the price of gold at the present day. Fifteen years later it had got down to $12.00 a pound and kept going down. In 1889 it was $2.00 a pound, in 1904 33c a pound and in 1911 the average price was 22c a pound. Clay gave up its “silver” at quite a low price.
Aluminium has increased enormously in the amount produced. In 1886 only one and one-half tons were reduced. Five years later the production was seventy-five tons and now it bids fair to attain the production of one hundred thousand tons.
Its lightness and strength suggest naturally its use for dirigibles or lighter than air ships. Its alloys have most interesting properties. In the Duren district, Germany, an alloy of the metal with copper, manganese and magnesium was produced which had such good qualities, that it is replacing other aluminium alloys, especially for the frames of dirigibles. The name duralumin is familiar to everybody, it is so frequently spoken of in the daily press. It is fair to say that very little unalloyed aluminium is used in a practical way; it is almost always alloyed with some other metal.
In reference to the modern kitchen, if we ask what are the great changes in the utensils of the chef, it would appear that they are pyrex, the glass which stands heat so well, and aluminium. The old time iron kettles were heavy and the tin kettles rusted. The aluminium ones which are substituted for them, are very light.
SOME of the more or less old-fashioned housewives were very proud of their copper pans and kettles. If these were neglected they would corrode and there would be danger of poisoning the food prepared in them, something which aluminium, except in exorbitant quantities of its compounds, will not do.
Following in the steps of Sir Humphrey Davy, and we strongly suspect in the steps of Faraday, most aluminium is now produced by electric power, by the electrolysis of one of its compounds called bauxite. This is dissolved or melted up with another compound of aluminium, sodium and fluorine, called cryolite. When a current of electricity is passed through the melted mixture, the aluminium very obligingly separates out from the bauxite, the cryolite being only slightly affected; although it contains aluminium it is but little decomposed, almost all the aluminum coming from the bauxite. There are great quantities of cryolite in Greenland and it used to be shipped from there by the cargo, but now it is produced artificially on the manufacturing scale.
If we go right down the line, aluminium will impress us as a very wonderful substance. It does all sorts of things according to the temperature and other conditions. The metal, when it approaches its temperature of fusion, is very brittle and can be easily reduced to powder. This powder mixed with a varnish-like vehicle constitutes aluminum bronze paint. It can also be beaten out until it is almost as thin as gold leaf. And now we come to a mechanical operation based on its affinity for oxygen.
If powdered aluminium is mixed intimately with chromium oxide, manganese oxide or iron oxide, the application of high heat to any portion of it, which may be very minute, will start a violent combustion of the aluminium and a reduction of the other metal, which reaction will automatically go through the mass, producing a very high temperature. It has been estimated
