Volume 8, Issue 9, 01 September 1937
Index of content:
8(1937); http://dx.doi.org/10.1063/1.1710346View Description Hide Description
``You know, it wasn't so long ago since Galileo was put into prison for saying that the world was round and that the sun was the center of the Universe,'' once said Ambrose Swasey. ``That was not so very much before my time, only one hundred and twenty‐five years before the birth of my grandfather whom I remember well. People now do not know much more than they did then.'' And yet people do know more on account of Ambrose Swasey for he built giant telescopes that pierced the depths of space and devoted his talents to science and engineering, leaving a lasting influence upon his age. On June 15, 1937, he died, a great task completed, four score and ten years of noble living.
8(1937); http://dx.doi.org/10.1063/1.1710348View Description Hide Description
8(1937); http://dx.doi.org/10.1063/1.1710349View Description Hide Description
8(1937); http://dx.doi.org/10.1063/1.1710351View Description Hide Description
Vacuum spark discharges between electrodes of several different elements were investigated by means of a camera and high speed rotating mirror. It was found that, with very rare exceptions, the luminosity always appeared at the anode before it appeared at the cathode.Measurements were made of the time interval between the appearance of luminosity at the anode and its later appearance at the cathode, and of the velocity of the luminous vapor from the anode. Evidence is given to show that positive ions from the anode have sufficient time to cross the gap during the average observed time intervals. Hypotheses are advanced of the mechanism of the discharge and to account for the observed vapor velocities. Apparently most of the phenomena observed after the formation of vapor at the anode can be accounted for by relatively low gap potentials.
8(1937); http://dx.doi.org/10.1063/1.1710352View Description Hide Description
Glass plates were found to be more difficult to break when an interval elapsed between marking and breaking. This was associated with a decrease in the strain. Apparatus for applying uniform force in marking glass is described; also, a device for studying breaking loads. Marked samples of glass were found to break when subjected to diminished loads for appreciable intervals. A correlation was shown between the breaking load and the load on the marker.
8(1937); http://dx.doi.org/10.1063/1.1710353View Description Hide Description
The construction of an electron diffraction apparatus is described, adapted to both reflection and transmission studies of crystalline materials and built in the laboratory at a moderate cost. This apparatus involves several novel features of construction and utilizes an electrode magnet for obtaining a homogeneous beam of electrons. The application of the instrument to chemical problems is illustrated by the results of a study of the effect of heat and of various gaseous atmospheres upon the structure of gold leaf. Microscopic, x‐ray and electron diffraction evidence indicate that at a temperature of about 400° the gold in a leaf flows into aggregates or larger crystal grains. This coagulation explains the contraction of the leaf as observed visually, the opacity of many patches in the heated leaf as observed microscopically, and the appearance of spots in the diffraction patterns. A ``many ring'' pattern observed when the leaf is heated in air or oxygen is attributed to the formation of an oxide which is rather unstable at about 400°. This observation clarifies some discrepant data in the literature.