By the application of the precise method developed by W. Swietoslawski for measuring the boiling points and the differences between boiling point of liquids and the condensation tempcrature of their vapors, it is possible to determine several facts of interest to the chemist. Among these are the purity of the substance under investigation, its boiling point, and the relation of boiling point to pressure.The normal hydrocarbons, pentane, hexane, heptane, and octane have been studied by this method. The ebulliometric control of purity of the preparations, the use of substances of high purity, and the application of a method of comparative measurements insure the accuracy of the results r eported.The numerical data are as follows: n-pentane, boiling point 36.077, ~~ =0.0391; n-hexane, boiling point 68.733 ddt =0.0420; n-heptane, boiling point 98.365, , P :! =0.0449; n-octane, boiling point 125.658, :! = 0.0477.

Isoprene (2-methyl-1,3-butadiene) has been prepared in a state of high purity. Physical properties determined on the freshly purified sample were as follows, boiling point, 34.076 ± .003° C; change of boiling point with change of pressure::~=0.0382° C per millimeter of mercury; freezing point, -146.8 ±.2° C; density at 20° C, 0.6805 ± .0001 g/ml; refractive index at 20° C, 1.42160 ± .00005. The molecular refraction was calculated to be 25.39. The volume expansivity was measured over the entire range of temperature between the freezing point and normal boiling point, giving the following equations: -3t+2.79 X 1O-6t2+ 4.31 X 10-0t3-5.60 X 1O-12t4) p=O. 7002 -0.9754 X 1O-3t-0.592 X 1O-6t2+ O.525 X 10-9t3+ 9.66 X 1O-12 t 4 ,

The differences between the boiling points of dilute aqueous solutions of heavy water and the boiling point of ordinary water were measured in the range from 0.3 to 7 percent of D 20. The boiling p oints were found to increase linearly with increa se in D 20, according to the equation mole % of D20 = 70.9 (tJ.T), where tJ.T is the boiling point in degrees centigrade minus 100. The measmements, made with ebulliometers of the type devised by W. Swi~toslawski, were found to offer a. rapid method for the analysis of solutions of heavy water.The differences between the boiling points and condensation temperatures of the same solutions were measured in a differential ebulliometer which gave a fractionation equivalent to about one theoretical plate. The small separation between the vapor and liquid lines on the boiling-point-composition diagram shows that the separation of heavy water by fractional distillation would require columns of extremely high efficiency.

No abstract

No abstract