  Warm absorbers are an important new tool for investigating the conditions
within the central regions of active galaxies. They have been observed in ~50%
of the well-studied Seyfert galaxies and have also been detected in quite a
number of Narrow-line Seyfert 1 galaxies (NLSy1). Here, we present a study of
the X-ray properties of several NLSy1s with focus on their warm absorbers: (a)
An analysis of all ROSAT PSPC observations of NGC 4051 including new ones is
performed, which reveals variability by a factor ~30 in count rate and much
less variability in the warm absorber parameters. (b) The possibility of a
dusty warm absorber in IRAS 13349+2438 is explored on the basis of
photoionization models for dusty warm gas and explicit ROSAT spectral fits. (c)
The X-ray spectrum of the NLSy1 1E0117.2-2837 is analyzed. It can be
successfully described by a very steep powerlaw of photon index G_x = -4, or
alternatively by a warm-absorbed flat powerlaw. UV-EUV emission lines expected
to arise from the warm material are predicted. (d) The strong spectral
variability of RX J0134.3-4258 (from G_x = -4.4 in the ROSAT survey
observation, to ~ -2.2$ in our subsequent pointing) is examined in terms of
warm absorption.
