G

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acquired any of the qualities by which steel is diftinguish-ed from iron.

7. A piece broken off from the fame ingot, weighingabout three quarters of an ounce, was treated in the famemanner with the powder for softening cast iron, viz. boneash with a small mixture of charcoal powder. The me-tal was found increased in weight about one thirty-fourth :it was less hard to the file than at first, but harder than thepart which had been cemented with the steel-making mix-ture.

It may be proper to observe, that cast iron is by nomeans a pure or simple metallic body, like those whose re-lations to platina have been examined in the foregoing ar-ticles. It teems generally to contain mineral sulphur, towhich perhaps its brittleness is chiefly owing, and whichis separated in the process by which the iron is made mal-leable. As platina appears incapable of contracting anyunion with pure sulphur, I have suspected, that while theplatina and cast iron unite together, some of the sulphure-ous matter is thrown out and consumed, and that the de-gree of toughness, observed in the compounds, may proceedin part from this cause; but experiments have not yet beencarried to a sufficient length to enable us to enter satis-factorily into disquisitions of this kind.

If however the cast iron should be as effectually purifiedby the platina, as it is even at the finery in the iron works,yet the toughness of the mixtures would still be pretty re-markable, considering how much platina, when its propor-tion is large, is disposed to diminish this quality in all theother metals. Perhaps platina, for certain purposes, mayprove a valuable addition to this most useful metal; a metalto which the workmen cannot communicate the hardnesswhich is often required, without communicating at thesame time brittleness and intractability.

XIV. Platina