Volume 5, Issue 6, 01 June 1934
Index of content:
5(1934); http://dx.doi.org/10.1063/1.1745242View Description Hide Description
X‐ray powder photographs have been made of an electrically heated nickel ribbon sealed into a thin‐walled glass bulb. X‐ray measurements extending from 450 to 1200°C showed no new high temperature crystal form of nickel. The thermal expansion of the face‐centered cubic lattice, present throughout the range investigated, is in agreement with macroscopic thermal expansion data.
The Charges on Droplets Produced by the Spraying of Liquids as Revealed by the Millikan Oil Drop Method5(1934); http://dx.doi.org/10.1063/1.1745243View Description Hide Description
5(1934); http://dx.doi.org/10.1063/1.1745244View Description Hide Description
5(1934); http://dx.doi.org/10.1063/1.1745245View Description Hide Description
Measurements of the velocity of sound vibrations in ice have been made in some detail both by direct and resonance methods. The velocity of longitudinal waves was measured directly on large bodies of ice. Blasting caps were used to create elastic disturbances and the time of travel was recorded by an electric seismograph placed at suitable distances. A plot of time against distance gives a remarkably straight line showing a velocity of 3410 m/sec. Laboratory measurements were made on long thin rods of ice which were excited by an oscillator and resonance frequencies measured both for longitudinal and torsional vibrations. The velocities for these vibrations are found to be 3163 m/sec. and 1913 m/sec., respectively. A formula is derived by which the velocity of longitudinal waves in a thin infinite plate can be found from these velocities. This formula gives a value of 3400 m/sec. which checks with that obtained directly by less than one percent. Various other elastic constants for ice are also deduced from these measurements. The values of Young's modulus and Poisson's ratio for ice are found to be 9.17×1010 dynes/cm2 and 0.365, respectively, in the range −5°C to −15°C.