J. Soc. Cosmetic Chemists 19 449-460 (1968) ¸ 1968 Society of Cosmetic Chemists of Great Britain Metrication The Royal Society Conference of Editors, which took place in December 1967, after considering the role that scientific journals can play in connexion with the Government's policy of promoting the general adoption of the metric system in the United Kingdom, has made two main recommendations: 1. That the system of units known as SI should be adopted in all scientific and technical journals. 2. That, in order to keep to a minimum the difficulties that will inevitably arise during the period of transition, the change-over should be effected as quickly as possible. The Council of the Society of Cosmetic Chemists of Great Britain has since decided that SI units shall be adopted in the British editions of the Journal from January 1969. SI (which is the abbreviation in many languages for Syst•me Inter- national d'Unit6s) is an extension and refinement of the traditional metric system. It embodies features which make it logically superior to any other system as •vell as practically more convenient: it is rational, coherent and comprehensive. The metric system •vhich had spread to several countries in the aftermath of the French revolution, began to be adopted in scientific work in the United Kingdom in the last quarter of the 19th century. Its use extended more and more widely, although a few branches of science remain where Imperial 449

450 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS units have continued to predominate. It is fortunate that now that the time has come to discard completely the time-honoured native units (which are not without their advantages), there is to hand a fully developed international system to take their place. Over the years much thought has been given to extending and improving the metric system until finally in 1960 the Conference G•n•rale des Poids et Mesures, the body responsible for maintaining standards of measurements (of which the United Kingdom is an active participant), formally approved SI. Already nearly 30 countries have decided to make it the only legally accepted system and it is clearly destined to become the universal currency of science and commerce. In many spheres in the United Kingdom (schools, universities, industry) the adoption of SI is being actively encouraged. The main features of SI are as follows: 1. There are six basic units (see below), the metre and kilogramme taking the place of the centimetre and gramme of the old metric system. 2. The unit of force, the newton (kg m s-2), is independent of the earth's gravitation, and the often confusing introduction, in some branches of science and technology, of g into equations is no longer necessary. 3. The unit of energy in all forms is the joule (newton x metre), and of power the joule per second (watt) thus the variously defined calories, together with the kilowatt hour, the B.t.u. and the home- power are all superseded. 4. 'Electrostatic' and 'electromagnetic' units are replaced by SI elec- trical units. 5. Multiples of units are normally to be restricted to steps of a thousand and similarly fractions to steps of a thousandth. Lists are appended of the basic SI units, of some derived SI units, of compatible units, and also examples of units which run counter to SI, the use of which is accordingly to be actively discouraged. Also listed are the names and symbols of the prefixes representing numerical factors: these are both convenient in obviating the need to write large numbers of zeros or in some instances high powers of 10, and also helpful in establishing familiarity with the numerical framework of modern science. It will be noted that the recommended prefixes are limited to 10 •3n.