PROOFS OF THE PROPERTIES OF IH0N.

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succeeded in producing an alloy of iron and mercury. * Themethod which this gentleman recommends for that purposeconsists in uniting an alloy of zinc and mercury with iron filings,and then adding muriate of iron, a decomposition now takesplace, and there is produced a muriate of zinc, and an alloy ofiron and mercury, which by kneading, and the aid of heat,assumes a metallic lustre.

Experiment V.

. Iron combines with oxigen in two different proportions only.

We have noticed already, (vol. I. p. 191) that iron burns withgreat splendor and rapidity in oxigen gas, and is at the sametime converted into an oxid. But it is capable, by other pro-cesses, of combining with two different portions of oxigen, andthese oxids are possessed of qualities essentially different fromeach other. These are the black, or the green ; and the red, orthe brown oxid of iron.

To illustrate this, let a bar of iron be brought to a red-heat;on cooling, its surface will be covered with thin scales, whichseparate by the blow of a hammer. If this process be continued,the whole bar may be converted into such scales, which arecalled forged scales of iron, or more properly, black oxid of iron.This is an imperfect oxid of iron; it contains about 27 per cent,of oxigen, and is obedient to the magnet.

If the imperfect oxid of iron, obtained in this process, bereduced to powder, and exposed to a white heat in a crucible,or under a muffle, stirring it frequently, it will become reddishbrown. This is the red, or brown oxid of iron. It is a perfectoxid, containing about 48 per cent, of oxigen, and is not affectedby the magnet. This oxid, ignited with charcoal, loses part ofits oxigen, and becomes re-converted into the black oxid of iron ;

Philosoph. Mag, 1802. No. LII. p. 406.