THE recently discovered ‘heavy water’, which has created so much interest in popular as well as scientific circles, is to be produced commercially in England. Plant has been developed at the Billingham works of Imperial Chemical Industries, Ltd., which is capable of producing a continuous supply of heavy water of approximately 30 per cent purity at the rate of 5 gm. per day, while approximately pure ‘heavy water’ will be produced at a somewhat later date. I.C.I, anticipate that they will be able to meet any commercial demand that may arise. Urey and Washburn, in the United States, discovered that the residual water in old electrolytic cells contained a larger proportion of heavy hydrogen than the normal. It was further found that by continued electrolysis, the concentration of the ‘heavy water’ was enriched, ordinary light hydrogen being given off preferentially, and ‘heavy water’ accumulating. This gave the key to a successful method of preparing ‘heavy water’ in quantity, and the electrolytic method is the one in use at Billingham. Large-scale production of ‘heavy water’ is only possible where exceptional resources of power and raw materials exist together. At Billingham, not only ordinary hydrogen in large quantities, but also residues in which ‘heavy water’ has accumulated, are readily available. These resources, together with cheap power and convenient research facilities, make Billingham a logical centre for the large-scale production of the new compound. Since its discovery in the United States, its probable uses are becoming more evident, and it is eloquent testimony to the vitality of British chemical technique that in so short a space of time it should have been translated from a scientific curiosity to a marketable commodity.