Determination of Vapor Pressures Below 10−3 mm Hg

Abstract
A method based on kinetic theory principles has been developed whereby the slope of the vapor‐pressure temperature curve of a liquid can be obtained at 25°C when the vapor pressure is of the order of 10−7 mm Hg at this temperature. A simple apparatus consisting of a boiler, slit system, and target is used to determine a dew point of the material under high vacuum. From the temperature of this dew point the slope can be calculated directly. If in addition a single value is known by other methods for the vapor pressure in the region of 10−3 mm then the value at 25°C is easily found. The results are believed to be accurate to 30 percent, as contrasted with other methods which give errors of several hundred percent in this region.

This publication has 3 references indexed in Scilit: