In order to measure accurately the effects of various elements on hardening of steel, experiments for gas hardening under varied conditions were carried out, using a special device invented by the author.
The effect of carbon upon carbon steel was first investigated, and then the influence of Mn, Ni, Cr, W, Mo, Si, Cu, V, Al, Ti, Co, Zr, Be and U on steel with a constant carbon content. The author having succeeded in the most accurate quantitative measurement on the effect of each element, the results are described in this paper.