[ 55 * 1

observed Sn weighing it, a part of the iron, equal to theacquired weight, must have been scorified and lost, andconsequently the volume of the metal diminished; so thatthere remained with the platina as great a weight of ironas at first under a less volume.

To satisfy myself whether the increase of specific gra-vity, or diminution of volume, was. owing wholly to thiscause, I made another mixture. But as cast ijxm is a veryimpure metal, I took a piece of a bar of the best forgediron, and cemented it with a mixture of wood foot andpowdered charcoal, till it had imbibed so much of the in-flammable matter as to become steel; repeating the ce-mentation, with a fresh mixture, till the steel melted. Themetal in this state was very brittle, so as without muchdifficulty to be reduced into powder. A portion of thispowder was mixed with charcoal powder, and meltedagain: 7000 grains of the steel powder, and 1000 grainsof platina, were likewise mixed with charcoal powder andmelted in a close crucible. The specific gravity of theforged iron was 7,795 ; which by the introduction ofphlogiston in the first cementation was diminished to7,618. By the repeated cementation and fusion, the gra-vity was diminished to very little more than 7. Of thepowdered steel melted with the charcoal powder, the gra-vity was 7,032, very nearly the same as before this lastfusion* Of the powdered steel and platina melted withcharcoal powder, the gravity was 7,760, which still ex-ceeds the computed gravity, though not in so great a degreeas that of th.e mixtures with as large proportions of castiron. The melted mixture weighed 30 grains less thanthe two ingredients before the fusion, on account, perhaps,of some small grains of the metal remaining dispersedamong the charcoal powder. Though this loss be sup-posed to have been of the steel only, yet, as there will re-main