In the course of investigations of the microwave absorption of polar substances in solution in nonpolar liquids, it was necessary to make careful measurements of the dielectric constants of the non-polar liquids. As these measurements are absolute determinations in contrast to the usual relative measurements carried out at radio frequencies and based upon the value of some liquid, usually benzene, taken as standard, it seems desirable to make the values generally available, although extreme precision cannot be claimed for them. The values also lead to conclusions of some theoretical interest.
Purification of Materialsn-Heptane from the Paragon Testing Laboratories was distilled in a four-foot packed column and the middle fraction drawn off. This fraction was then dried over sodium wire from which it was subsequently distilled. The middle fraction was used; h. p,, 97.60-97.68' a t 753 mm., nmD 1.38824; lit.,2 b. p. 98.4', nmD 1.38774. C. P. benzene from the City Chemical Corporation, New York, was twice fractionally crystallized and dried over sodium wire. It was distilled in a four-foot colum; and the middle fraction collected; a t 760.9 mrn.; nmD 1.50092; lit.,a b. p. 80.07", nZoD 1.50096.Cyclohexane from the Paragon Testing Laboratories was distilled in a four-foot column and the middle fraction dried over sodium wire. This fraction was distilled after drvine and the middle fraction drawn off: b. D.. 80.30-b. p., 79.80-79.85 80: 40' at 760 mm., nzoD 1.42656; iit.,4 b. p.; h017" a t 760 mm., n% 1.42648. Carbon tetrachloride' from the Geo. A. Rowley Co., Philadelphia, was shaken with concentrated sulfuric acid, washed with separate portions of dilute sodium carbonate solution, then washed with distilled water until free from alkali, and dried over calcium chloride. The sample was distilled in a four-foot packed column and the midd! fraction collected; b. p. 76.60-?6.70", m. p., -22.8 , ~' O D 1.46075; lit.,6 b. p. 76.66 , m. p. -22.81', @D 1.46048.Carbon disulfide was shaken with aqueous potassium permanganate solution (5 g./liter) and permitted to stand for thirty minutes. After separation with a separatory funnel the sample was shaken with mercury and then with successive portions of aqueous mercuric sulfate until free from the characteristic rancid odor. The sample was dried over calcium chloride and distilled through a four-foot packed column; b. p., 46.15-46.18' a t 762.6 mm.; lit.,' b. p. 46.25" a t 760 mm. * Harvard University Ph.D. 1921.(1) This research was carried out with the support of the Office of (2) Egloff, "Physical Constants
