In working aluminum I have found it to be a splendid substitute for malleable iron, especially in many cases where the iron could not be procured in time, or when it came so warped as to be unfit for use. I have never been able, however, to get castings which would come quite up to the strength claimed for it; the most satisfactory grade was that of ten-per-cent. aluminum, which by the way is very hard to work, especially in drilling. There is no doubt, however, that it can be made to take the place of steel in many instances. A knowledge of aluminum is a great boon to experimenters, as it will probably come into quite general use with the manufacturer. The ten-per-cent. aluminum finishes very handsomely, and in olden times it would have been a splendid substitute for the brass hubs then so common. As an antifriction metal it is unsurpassed by any of the bronzes. It casts bright and sharp, but shrinks amazingly, although not dangerously; at least I have never had a part of the casting drop off, as in malleable it often does, and though the aluminum sometimes leaves a great depression in the heavy part of the casting, it causes no sponginess underneath. It can be readily bronzed or soldered. Aluminum bronze drawn into wire will make very good spokes, and it has been used for this purpose to some extent in England. All tendency to rust is obviated, and it saves all nickeling; it resists corrosion sufficiently well to dispense with any covering, but it does not look as well as a nickel finish. No better authority on the subject can be had than that of the Cowles Catalogue; useful information also can be gathered from “Richards’s Aluminum,” and “Thurston’s Material of Engineering.” The last-named treatise speaks on the subject as follows: “The alloys of aluminum are very valuable. Its remarkable lightness, combined with its strength, makes it useful as a constituent of those alloys in which strength and lightness are the needed qualities. It has a pleasant metallic ring when struck, and confers a beautiful tone when introduced into bellmetal. “Aluminum may be added to bronzes and brasses with good results. The alloys (copper ninety per cent., aluminum ten per cent.) may be worked cold or hot like wrought iron, but not welded. Its tenacity is sometimes nearly one hundred thousand pounds per square inch. Its specific gravity is 7.7. In compression this alloy has been found capable of sustaining a little more than in tension,—one hundred and thirty thousand pounds per square inch (nine thousand one hundred and thirty nine kilos per square millimetre),—and its ductility and toughness were such that it did not even crack when distorted by this load. It is so ductile and malleable that it can be drawn down under the hammer to the fineness of a cambric needle.