This book deals with the methods of X-ray production at a level which is accessible to advanced undergraduates and researchers who use X-rays. It also discusses the fundamentals of these physical properties from an experimental viewpoint which is not covered in more specialised texts. The book begins with a survey of work carried out before 1945. Continuous and characteristic spectra are discussed followed by a description of techniques used in their study. Further studies of production, absorption and scattering in atomic and nuclear processes are described, including a completely new chapter on X-ray production by protons, alpha-particles and ions. The concluding chapter surveys some more advanced fields of study. It will be very valuable to all research and industrial physicists working with X-rays who need to know about their fundamental properties in more detail. In this second edition SI units are used throughout and the material reflects the changes in the use of X-rays and the developments in the field.

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Carbon monoxide labeling with O15 was produced by passing O15, made in the Medical Research Council's cyclotron, over charcoal at 1000° C. After a single breath of the radioactive gas the rate of fall of activity during apnea was measured by external counting in different regions of the lungs of normal subjects in the sitting position. The carbon monoxide ‘clearance rate’ calculated from these data is proportional to the diffusion per unit volume in the zone under study. There was a gradient of diffusion per unit volume, the highest value being found in the basal regions of the lung and much lower values toward the apex. On exercise the clearance rate in the upper zone increased to a value similar to that in the lower zone at rest; the clearance rate in the lower zone was unchanged. Measurements of the O15clearance rate showed a similar gradient but on exercise both upper and lower zone values increased so that the gradient was maintained. The results are interpreted as showing that in the resting state all the basal capillaries are open but that the proportion of patent capillaries diminishes toward the apex. On exercise there is an increase in flow at both apex and base and in consequence the remaining apical capillaries open. Submitted on December 21, 1959