The time devoted to collecting and plotting emulsion calibration data can be reduced considerably by the use of a new transmittance scale which is logarithmic from 1 to 30 percent and which then expands non-uniformly to 97 percent. Data are presented from seven independent laboratories which establish the approximate linearity of the emulsion calibration curves for Eastman SA-1 films, SA-1 plates, SA-2 films, I-N plates, and 33 plates. The practical uses of this scale on plotting boards and in a special emulsion calibration paper are discussed.
In certain cases, all emulsion calibration procedures can be eliminated. A transmittance slide rule for use in the quantitative determination of tetraethyl lead in gasoline is described.
HAROLD K. HUGHES and R. W. MURPHY, "Emulsion Calibration Scale for Quantitative Spectroscopic Analysis," J. Opt. Soc. Am. 39, 501-502 (1949)