THE work that Prof. D. Hanson and his co-workers have been carrying out on the effect of various impurities on copper of the highest degree of purity is extended in two papers read recently before the Institute of Metals. The first of these, in collaboration with Miss G. W. Ford, deals with the influence of bismuth, the solubility of which in solid copper is less than 0 002 per cent. Small amounts of this element adversely affect the rolling properties of copper, particularly during hot-rolling, and the limiting percentage for this process appears to be less than 0.01 per cent. In cold-rolling, the material fractured when more than about 0'05 per cent. of bismuth was present. Even with smaller amounts the effect is bad, especially where the degree of cold-work is great. The effects of this impurity on the electrical conductivity and tensile strength are small.