obtained UV and visible light spectra of IC 351 that show it to be a high excitation nebula, but without the presence of the usual silicon lines, and suggest that the silicon atoms could be locked up in grains.

Our spectrum (Figure 9) taken centered on the PN suffers somewhat from an incomplete subtraction of OH airglow lines, due to the sky frames not being taken properly for the on-source images. The OH lines show up in emission mainly in the H and K-band portions of the spectrum. However, the major features of and emission lines can be seen.

### IC 418

The spectrum of this well-studied young, low-excitation PN was previously shown to be dominated by lines of and in the near-IR, with a hot dust continuum (Willner et al. 1979; Zhang & Kwok 1992; Hodapp et al. 1994). Hora et al. (1993) and Paper I showed broad- and narrow-band near-IR images of the PN, showing the elliptical, double-lobed structure in the IR.

Three positions in the nebula were observed to determine the spectral variations across the object. The positions observed were on the central star, the peak of the E lobe, and in the E halo region outside 