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Overall costs of £20,000 a day for operating the very largest tankers make it important to extend the period between drydockings as much as possible, to keep the time spent in port to a minimum, and to avoid even small losses of speed in service.

Although cathodic protection of copper sheaths on wooden ships was proposed and practised over 100 years ago and the use of zinc protectors near bronze propellers on steel ships has been common for many years, it is only in about the last ten years that the present techniques of cathodic protection of ships’ hulls have been developed. Much study has been devoted to the design of the installations, including type and composition of anode materials, number, size, shape and position of anodes, and designers specialising in this field now have considerable practical and theoretical knowledge of such matters. Another factor which must be taken into consideration is the choice of coating for the bottoms of cathodically protected ships, particularly on areas close to the anodes; this is discussed in the present paper.

Shipping is one of the major British industries and a valuable source of ‘invisible exports’ by virtue of its earnings of foreign currencies. One of the major costs incurred by shipping companies is that of preventing the corrosion of their vessels and at a rough estimate it is probable that something like £30 million is expended annually in countering the corrosion of ships and harbour installations. Ships are constructed mainly of steel and their protection is essentially a particular aspect of the problem of protecting steel against corrosion. Aluminium alloys and newer materials such as plastic sheets are being increasingly used on board ships, but these materials do not offer quite the same difficulty as regards protection nor is the problem yet of the same magnitude. Painting is the most widely used means of protection and the present article deals with some of the problems associated with the painting of ships from the point of view of a paint manufacturer.

Over two years ago the first issue of CORROSION TECHNOLOGY appeared. In the 25 issues that have followed we have published over 90 major signed articles, 250 commentary items, 250 abstracts of corrosion literature and hundreds of other items and features, all dealing directly or indirectly with problems of corrosion. During its comparatively short life, CORROSION TECHNOLOGY has grown up and made many contacts throughout the world. To mark the achievement of our first 24 months' publication we invited some of our friends from the worlds of science and industry to set down a few of their thoughts on corrosion matters for publication in this issue, and we are privileged to be able to print the following contributions.

CORROSION COMMITTEE'S SIXTH REPORT. The purpose of a joint meeting of the Iron and Steel Institute and the Society of Chemical Industry, held last month at Church House, Westminster, was to discuss the Sixth Report of the Corrosion Committee of the Iron and Steel Institute containing an account of the researches carried out by that committee over the past twenty years.

WITH record attendances during the first days of the Motor Show this year, Exhibitors are asking if it would not be possible to have certain times, or days, reserved for trade buyers. The promoters are obviously concerned with any possible loss of gate money, but it is very true that at times, when stands are crowded with mere sight‐seers it is very difficult for genuine potential buyers and trade personnel to see what they want in the short time that may be at their disposal. These record attendances may not be repeated always; this year is the first time for a long time that anyone can order any car with a reasonable delivery date, and most cars with only a few weeks wait.

Sprayed metal coatings have a characteristic structure which greatly influences their behaviour in corrosion processes. The coatings are built up from tiny particles of metal, of the order of 20 microns diameter, produced by atomising molten metal in a stream of compressed air. The metal is supplied to the spraying pistol either as a wire or a powder and is melted in an oxygen‐fuel gas flame. The metals of low melting point, including zinc and aluminium, are also applied by a pistol which receives molten metal from a heated reservoir.

SOUTH AFRICA COMBATS CONCRETE DETERIORATION. PROBLEMS of concrete deterioration through corrosion are being tackled in the Union of South Africa where concern has been shown at the costly repair and replacement bills for, particularly, bridges and municipal sewers.

Paint has long been used for the protection of iron and steel against corrosion.

THE EXTENSIVE use of steel can be attributed to its many physical and mechanical properties and low cost when compared to other materials. It has, however, one major disadvantage in that it will corrode in many environments.