Electronmicroscopic mass determination using photographic isodensity techniques

Using Agfacontour, Kodalith, or similar films, it is possible to convert an electron micrograph into a map of regions of equal photographic density (isodensitites) by simple copying procedures. If images of polystyrene spheres and a calibrated density wedge are included in the copies, it is possible to quantitatively calibrate the isodensities in terms of mass per unit area of the specimen. In this way, electronmicroscopic mass determination may be accomplished without the need of densitometers or other photometric equipment.