Abstract
Photoelectric spectrophotometry of emission lines in the 3700-7400 A region is presented for the planetary nebulae (PN) in M15 (K648) and for the PN in the direction of the north galactic pole 49 + 88 deg 1 (H4-1). He, C, N, O, Ne, S and Ar abundances are given with respect to H. The high carbon abundance in H4-1 indicates that PN are ejecting carbon rich material into the interstellar medium, and the underabundances of Ne, S and Ar relative to O in H4-1 indicate either that the oxygen enrichment of the interstellar medium at the early phases of our galaxy proceeded faster than Ne, S and Ar enrichment, or that some O in the shell has been produced by the central star.
