Two units for semi-continuons vacuum melting are mentioned : one diseribed by G.H. Moore of National Research Corp, and the other designed by the auther. An action of magnesia crucible on the melting of iron and its alloys in vacuo is also described on the basis of G. Hochmann and Moored's deta.
As the clemand for high purity meta ls is increasing, there are many advantages and applications in the vacuum fusion technique with which small traces of oxygen, hydrogen and nitrogen in these metals can be determined. In this articleg the principle and problems of the vacuum fusion technique are discussed and the applications of this method are reviewed.