Karsten found that by the addition of 15 per cent. of fine silver to iron during the refinery operation, the quality of the iron was sensibly deteriorated: it did not forge well, became scaly, the bars presented cracks at the edges, and otherwise resembled hot-short iron. Analyses showed that it contained 0.034 per cent. of silver. It would appear, therefore, that silver has the same influence as sulphur upon iron, although in a less marked degree.
Iron and arsenic may be combined by fusion in any proportion. When the amount of arsenic is large, the magnetic character of the iron disappears. The alloy of these metals is more or less white, hard, brittle, and fusible, according to the amount of arsenic. It is crystallizable, its fracture more dense, and the texture closer than that of iron; according to Achard, similar to that of steel. Cadet asserts that this alloy will receive a brilliant polish, and that articles of jewellery are made from it.
Iron has a great affinity for chromium, and the 2 metals form alloys in all proportions. These compounds are generally hard, brittle, crystalline, of a greyer white than iron, of considerable lustre, less fusible, much less magnetic, and very much less soluble in acids than iron; the characters are the more prominent in proportion to the amount of chromium.
The alloy, composed of Iron . 69600 0.83 5 at. Chromium 351.82 0.17 1 „ is nearly of a silver-white, with a fibrous texture, not easily yielding to the file, and very brittle. Merimee, with the aid of a cutler, tried 2 different alloys prepared by Berthier, the one containing 0.010 chromium, the other 0.015. Both forged extremely well; the former indeed appeared more easy to forge than pure cast-steel. Blades were made out of them for a sword and razor, and both were found to be of excellent quality, their edges being hard and lasting. But the most remarkable characteristic was the readiness with which this alloy received a beautiful damascening when rubbed with sulphuric acid. This damascening presented an agreeable variety of veins of a very brilliant silver-white, much resembling that which is obtained from steel alloyed with silver. The white parts, according to Berthier, are probably pure chromium, upon which the strongest acids have scarcely any action. In the Chrome Steel Works of Brooklyn, the chrome-iron ore is ground fine, and reduced with powdered charcoal in crucibles. The resulting mass is carefully weighed, ground, mixed with Swedish or wrought-iron, and melted in crucibles in charges of 75 lb. In 24 hours, the contents of 6 crucibles can be melted.
The hardness of the resulting steel depends on the amount of chromium contained, which may vary from 0.25 to 2 per cent.
Copper, according to Karsten, may combine with any proportion of iron, augmenting its tenacity and hardness. Rinmann, for this reason, thinks that it would make, with raw cast-iron, an excellent alloy for anchors, mortars, anvils, cylinders, etc. 200 parts grey cast-iron, and 10 of red copper in thin shavings, immersed in linseed-oil, and submitted, with the addition of charcoal, to a very hot forge fire during 25 minutes, yield, according to Rinmann, a homogeneous metallic button, composed of 104 Iron, 6 copper. This alloy is very hard; its density is 7*467. His experiments show that 200 parts copper and 10 of grey cast-iron, treated in the same way, yield a homogeneous button very ductile when cold. With 16 of copper and 1 of raw cast-iron, he obtained a ductile alloy that was magnetic, and resisted the file better than pure copper; the surface and fracture were of a fine red colour. Finally, 8 of copper and 1 to 4 of iron, give alloys which are harder than the preceding, but not perceptibly more brittle nor less coloured than copper. According to Lavoisier, iron containing copper possesses greater tenacity than any other, and becomes brittle only in the stages between a brown-red and deep-red heat: above or below this temperature it can readily be forged.
Berthier affirms, in like manner, that iron containing copper possesses great tenacity when cold, but that it is brittle when hot, and can be forged only when above a reddish-white heat or below a cherry-red heat. It is probable, he says, that a large proportion of copper, 1 per cent. for example, would give the cast-iron additional tenacity, and make it better fitted to be employed in castings.
According to Dumas, tin enters into alloy with iron in ail proportions. Heated to a high temperature, they melt; but at a moderate heat, separation takes place - a species of liquation. At first a quantity of pure tin, more or less considerable, is melted; then tin alloyed with iron; and there finally remains a less fusible alloy, consisting of tin and iron in other proportions, the iron predominating. Berthier states that a very small quantity of iron is sufficient to diminish the malleability of tin, blemish its white colour, and render it hard. The 2 metals enter into direct alloy when their oxides are heated with either charcoal or black flux. The alloy composed of Tin .... 0.351 1 at. Iron .... 0.649 4 „ is of a clear iron-grey colour, crystalline, and sufficiently brittle to be reduced with ease to an impalpable powder. The alloy composed of Tin.....0.50 Iron.....0.50 is of a greyish-white colour, very brittle, with a granulated fracture. According to Bergmann, Karsten, and others, by melting iron with tin, 2 distinct and definite alloys are always obtained: the one composed of 21 tin and 1 iron; the other of 2 iron and 1 tin.
The former is very malleable and harder than tin, without being so brilliant; the latter is not very malleable, and too hard to be pared with the knife.