The recent history of the X-ray absorber in NGC 3516

We present two BeppoSAX observations of the bright Seyfert 1 galaxy NGC 351 6, performed four months apart (late 1996-early 1997). The earlier spectrum is considerably weaker and harder in the whole 0.1-50 keV energy range. In addition, the warm absorber oxygen features, which were already observed w ith ROSAT and ASCA, are much less pronounced. The most straightforward expl anation is that in 1996 November NGC 3516 was being seen through a substant ial (N-H similar or equal to 10(22) cm(-2)) column of cold material. This i s the first confirmation with modem instrumentation that NGC 3516 indeed un dergoes phases of strong cold X-ray absorption. We speculate that these int ervals may be connected to the onset of the remarkably variable UV absorpti on system, making NGC 3516 the best known example of a low-luminosity broad absorption line (BAL) quasar. The absorbing matter could be provided by cl ouds ablated from the rim of the circumnuclear molecular tours, seen at a r ather high inclination angle.