ABSTRACT
Researches on electricity in rarefied gases and selenium continued during the period 1878–1884. The work of Crookes (99), his lectures (120), and his bold views on the fourth state of matter, along with the researches and contrasting theories of Wiede-mann (150) and his compatriots, prompted more intensive researches into the nature of cathode rays. Refinements in the design of vacuum pumps by Gimingham (99) and others provided the ever-lower pressures necessary for progress in this work.
