The dielectric coefficients of gases III—Allene, allylene, butanes, butylenes, cyanogen, and hydrogen cyanide—IV— Fluorides of boron, nitrogen, and carbon

Measurements of dielectric coefficient similar to those recorded in Parts I and II have now been made for the gases allene CH2 = C = CH2, CH3—C≡CH, n- and iso-butane, α-, β-, and iso-butylene, cyanogen, hydrogen cyanide, boron trifluoride, nitrogen trifluoride, and carbon tetrafluoride, using the same apparatus as before. Owing to the stability and the ease of working with parallel condensor described in Part II, this was employed exclusively, the condeser G4 being used to contain the gases. Of these, allylene, iso-butylene, and hydrogen cyanide have appreciable moments, while α-butylene, nitrogen trifluoride, and possibly allene appear to be very slightly polar. The other gases are electrically neutral. β-butylene is of interest since it affords a rather rare example of a gas exhibiting cis-trans isomerism. Unfortunately, the raw material required for making the cis form could not be obtained while the experiments were in progress, so that the measurements have had to be deferred.