THE SPECTRUM OF THE PLANETARY-NEBULA IC-351

International Ultraviolet Explorer (IUE) and optical region spectrosco pic observations are presented for the moderately high-excitation plan etary nebula IC 351. Most of the atoms are distributed over a narrow r ange of ionization. Thus [N II] and [S II] are weak; [Ne IV] is promin ent, but [Ne V] is missing. It appears that the metal/hydrogen ratio i s smaller than in the Sun. No Si lines are seen either in optical or U V regions. It is suggested that virtually all Si atoms are locked in g rains. The ionization correction factor method fails utterly for N, fo r example. Hence IUE data are essential for chemical composition estim ates. Until high spatial resolution images are available, construction of a new theoretical model does not seem warranted.