Abstract
A revised chart of mAs. was drawn based on experiments on the relation between X-ray intensity and development time. The process of drawing up and the confidence limit of the chart, the relation between development time and contrast and that between development time and fog were explained here. These relations were provided by the examination of photographs. Moreover, the following points on the use of this chart were explained. 1) to revise the condition of radiography. 2) to revise the contrast. 3) to revise the intensification factor of the intensifying screen.
