XI. Preliminary note on the constant of electromagnetic rotation of light in bisulphide of carbon

Abstract

In connexion with other work upon current measurement by Mrs. Sidgwick and myself, we have endeavoured to determine the value of this constant, so as to decide between the very discrepant results arrived at by Gordon and by H. Becquerel. The method adopted by us was so far similar to that of Gordon that the tube of bisulphide of carbon was placed inside a helix, but the value of the current traversing the helix was determined in a different manner without reference to terrestrial magnetism. The light employed was that emitted by sodium. When it is remembered that the effect would vary about two parts per thousand in passing from one sodium line to the other, the importance of definiteness in this respect will be obvious.