Aluminum is found not only in clay and indeed in most rocks except sandstone and limestone, but also in several of the precious stones, in the yellow topaz, the blue sapphire and lapis-lazuli, and the red garnet and ruby. It might look down upon some of its metallic relatives, but it is friendly with them all, and perfectly willing to form alloys with most of them. A single ounce of it put into a ton of steel as the latter is being poured out will drive away the gases which often make little holes in castings. Mixed with copper it makes a beautiful bronze which has the yellow gleam of gold, but is hard to work. When a piece of jewelry looks like gold, but is sold at too low a price to be "real," it may be aluminum bronze, very pretty at first, but before long its luster will vanish. Aluminum bronze is not good for jewelry, but it is good for many uses, especially for bearings in machinery. Aluminum mixed with even a very little silver has the color and brightness of silver. The most common alloys with aluminum are zinc, copper, and manganese, but in such small quantities that they do not change its appearance. With so many good qualities and so few bad ones, it is small wonder that aluminum is employed for more purposes than can be counted. A very few years ago it was only an interesting curiosity, but now it is one of the hardest-worked metals. Automobiles in particular owe a great deal to its help. When they first began to be common, in 1904-05, the engines were less powerful than they are now made, and aluminum was largely employed in order to lessen the weight. Before long it was in use for carburetors, bodies, gear-boxes, fenders, hoods, and many other parts of the machine. Makers of electric apparatus use aluminum instead of brass. The frames of opera glasses and of cameras are made of it. Travelers and soldiers and campers, people to whom every extra ounce of weight counts, are glad enough to have dishes of aluminum. The accommodating metal is even used for "wallpaper," and threads of it are combined with silk to give a specially brilliant effect on the stage. It can be made into a paint which will protect iron from rust; and will make woodwork partially fireproof.