High-Vacuum Equipment

Abstract

A BOOKLET issued recently by Messrs. W. Edwards and Co. (London), Ltd., Kangley Bridge Road, London, S.E.26, specialists in the manufacture and provision of high-vacuum equipment since their formation twenty-five years ago, describes briefly the range of products now available. High-vacuum processes are no longer of interest solely to the specialist, for in recent years there has been an astonishing growth in laboratory and industrial applications of high-vacuum technique ; hence, in addition to a wide range of the essential components of any vacuum system (rotary backing pumps, diffusion pumps, vacuum measuring instruments, and accessories), complete vacuum plants, combined mobile units, and vacuum pipe-line units, suitable for schools, laboratories or works, are now available. Special vacuum plants listed include : vacuum coating equipment, for depositing thin films of precious and other metals, alloys and non-metallic materials on metallic and non-metallic bases by the evaporation or cathodic sputtering techniques ; electron diffraction equipment, suitable for the investigation of surface structure ; vacuum sublimation and centrifugal freeze-drying equipment, designed specially for the production of ampoule quantities of dried pharmaceutical and biological materials. Developed in conjunction with Dr. R. I. Greaves, this freeze-drying plant utilizes his special technique, consisting of centrifuging in vacuo the material to be dried, whereby rapid freezing and sublimation results without frothing, a process which Dr. Greaves successfully employed for his work on blood plasma drying during the War and which has already been described in these columns (Nature, 153, 485 ; 1945).