The spectrum of doubly ionized carbon, CIII

With new experimental data 54 lines of CIII have been classified. A large number of these lines involve terms in which both valence electrons are excited. The ionization potential deduced from this classification is 47.7 volts. The classification of a few additional CII lines is also given. These analyses fix the relative position of the singlets and triplets in CIII and the doublets and quartets in CII.