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.
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