Volume 2, Issue 2, 01 February 1932
Index of content:
2(1932); http://dx.doi.org/10.1063/1.1745031View Description Hide Description
A method of studying the progressive crystal lattice changes occurring in a series of alloys or mixed crystals is described. This method compares the Bragg angles of x‐ray reflection from a standard crystal with those of the crystal being studied. The important features of the method are simplicity and high accuracy (0.002 percent), which is attained without the use of an accurately calibrated angle scale. The theory of the method is discussed and two examples of experimental data which have been obtained are given.
2(1932); http://dx.doi.org/10.1063/1.1745032View Description Hide Description
2(1932); http://dx.doi.org/10.1063/1.1745033View Description Hide Description
The nature of electrical conduction in paper is discussed, particularly with regard to the formation of potential discontinuities. Experiments are described which indicate the formation of soft x‐rays in paper insulated cables under voltage. Methods of measurement of potential distribution in paper insulation are given, together with preliminary results, which show large electrode drops under certain conditions. The relation of these experiments to those of Reboul and Bodin is pointed out.
2(1932); http://dx.doi.org/10.1063/1.1745034View Description Hide Description
The power factor, dielectric loss and capacitance at 60 cycles of abietic acid have been measured over the temperature range 20° to 100°C. Short time charge and discharge curves, beginning 0.001 sec. after the application or removal of voltage, taken with the amplifier oscillograph, have permitted direct measurement of the relaxation time over the same temperature range. It is shown in general that there are two principal components of the discharge curve which lead to two types of relaxation time, one being the principal factor in the dielectric loss at low temperatures, and the other at high temperatures. The discharge curves have been used for an analysis of the alternating current behavior following the method of von Schweidler. There is uniform agreement between measured and computed loss. With increasing temperature the dielectric constant rises from about 2.6 to 2.8 within the temperature interval 20° to 50°C, the maximum rate of rise being at about 30°, at which temperature the maximum of power factor is also observed. The results are discussed in the light of dielectric absorption in the Maxwell sense and of Debye's theory of polar molecules. The conclusion is reached that alternating currentmeasurements at 60 cycles do not offer a promising method of distinguishing between the two theories, since the same behavior is predicted by each.
2(1932); http://dx.doi.org/10.1063/1.1745035View Description Hide Description
For calculating the flow of heat through walls of buildings the steady state formula based upon average temperatures has been found inadequate. A solution for the periodic heat flow through such walls is given, which has been simplified so that it depends upon two dimensionless quantities f and β1, which are functions of the physical properties of the walls and the periodicity. Curves are given which make it possible to read off the solution directly as soon as f and β1 are known. An experimental check is given.