  The gravitationally lensed quasar B1600+434 (z=1.61, mV=21.6) has been
observed at the 2.56m Nordic Optical Telescope (NOT). In this Letter we report
the discovery of an edge-on late-type galaxy located between the two lensed
components (separation 1\farcs4), close to the fainter image. The galaxy
photometry indicates that its redshift is approximately 0.4. We detect a large
colour difference between the two images due to significant obscuration of the
faint image. The estimated amount of absorption as a function of colour
indicates that the extinction may be due to dust in the lensing galaxy. We also
present evidence of flux variability in B1600+434 with a detected change of
0.25mag in one year. The theoretically expected time delay is of the order of
one month and so the system may be an interesting object for determining the
Hubble constant.
