Abstract
The spectrum of arsenic has been examined under varying conditions of excitation, and lines belonging to the singly-ionized atom have been identified. Combinations between the deep terms of the singlet and triplet system of As II have been discovered; about 70 lines have entered into the classification. A provisional term scheme, based on two members of the singlet series 5s1P - mp1D, is set up. The largest term 4p3Po (v 162788) leads to an ionization-potential of about 20.1 V.