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Thus, Sir William and Lady Huggins photographed several ultra-violet oxygen lines in Beta Lyræ, and found in Rigel signs of the presence of nitrogen, which, as well as silicium, proves to be a tolerably frequent constituent of such orbs. For some unknown reason, metalloids tend to become effaced, as metals, in the normal course of stellar development, exert a more and more conspicuous action. Dr.
In view of the fact that samples of cast iron with equal percentage of silicium and carbon yield on casting a different product, it has become necessary to institute experiments as to the cause of this behavior.
Hydrogen, which forms two-thirds of water, and enters into some mineral substances, is perhaps next. Nitrogen, of which the atmosphere is four-fifths composed, must be considered as an abundant substance. The metal silicium, which unites with oxygen in nearly equal parts to form silica, the basis of nearly a half of the rocks in the earth's crust, is, of course, an important ingredient.
Cast iron free of silicium yields on cooling the entire amount of carbon in the amorphous state, while presence of the former metal gives rise to the formation of graphite, and, consequently, causes a partial separation of carbon. Iron suffers on casting loss of graphite, assumes a finely-grained texture, becomes hard and brittle, and is changed from gray to white.
Such proportions will make a soft, even grained, dark gray iron, whose crystals are small and bright, and whose fracture will be uneven and sharp to the touch. The phosphorus in this instance gives the metal liquidity at a low temperature, but does not seem to influence the crystallization to any appreciable extent. The two elements to be avoided by the founder are silicium and sulphur.
On remelting of cast iron, increase in tensile strength was observed, which attained its maximum in iron with a small percentage of silicium after the third, and in such with a large amount after the fourth melting. The increase in tensile strength was accompanied by a loss of silicium, graphite, and manganese coupled with a simultaneous augmentation of combined carbon.
From trials conducted by Ledebur, it appears that cast iron is rendered suitable for foundry purposes i.e., to fill the moulds well and to yield sharp and definite forms free of flaws, to be cut with a chisel, and turned on a lathe through a certain percentage of graphite, whose presence depends on that of carbon and silicium.
The great mass of the earth was shown to be composed of metals in combination with oxygen, to which they are united in one, two, or more definite and unalterable proportions, forming compounds which are termed metallic oxides, and these, again, combined with oxides of other bodies, essentially different to metals, namely, carbon and silicium.
Fusing with silicium would give a gold-silicide that might fill the bill for hardness; but I can't even make a guess as to how they do the tempering. Ask the Colonel what the whole process is, Professor. It will make a capital paper to read before the Institute of Mining Engineers at their next meeting."
So long before being forwarded to Tampa Town, the iron ore, molten in the great furnaces of Coldspring, and brought into contact with coal and silicium heated to a high temperature, was carburized and transformed into cast iron. After this first operation, the metal was sent on to Stones Hill. They had, however, to deal with 136,000,000 pounds of iron, a quantity far too costly to send by railway.
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