A MEMBRANE FILTER TECHNIQUE FOR GLASS FIBRES*

摘要

The phase-contrast techniques used in counting asbestos fibres are difficult to apply to glass fibres because of the low contrast of the phase image. To overcome this difficulty filters were treated and examined in different ways. The most satisfactory proved to be low-temperature ashing of sectors attached to glass slides by acetone vapour followed by microscopical examination using simple Köhler illumination. This technique yielded Counts approximately twice those obtained from standard phase-contrast evaluation