The suitability of using the White cell for determining the extinction coefficient of liquids was examined by measuring the attenuation of electromagnetic radiation, in the visible part of the spectrum, through distilled water. The analysis of the transmittance measurements through liquids in a White cell does not provide a sufficient number of independent equations to solve directly for the extinction coefficient. Reasonable estimates however can be made by employing a correction which accounts for changes in the mirror reflectance due to a liquid-mirror interface.
The reduction in the transmittance of distilled water due to an oil film was studied for fuel oils number 2 and 3 and midwestern crude oil. Reduction depends on the thickness and the extinction coefficient of the oil. It was found that a small film of crude oil, approximately six thousandths of an inch thick, can reduce the transmittance to almost zero in the range where the water\u27s transmittance is a maximum (0.45µ - 0.50µ).
Errors resulting from using transmittance measurements to determine the extinction coefficient of liquids were examined. The analysis reveals that transmittance measurements through two cells which differ in their optical path by 1.3 will yield the highest level of accuracy --Abstract, page ii
