  We present a high S/N ratio optical spectrum of the bright quasar
HS1700+6416. These data usefully complement the UV HST data from Vogel and
Reimers (1995). We analyse the metal line systems using photo-ionization models
allowing for inhomogeneities in the gas. The models are able to reproduce
within a factor of two the large N(HeI)/N(HI) ratio together with the mean
column densities of the heavy element species observed in the z=2 systems. The
density contrast between low and high density regions is of the order of 30.
Although the [O/C] abundance ratio seems slighly larger than solar, firm
conclusion should await higher spectral resolution data. A break at the HeII
ionization limit of a factor of ten is acceptable in the ionizing spectrum.
Abundances are found to be about 0.08 solar. This together with other
determinations from the literature indicates that there is evolution in the
metal content of metal line systems with redshift: [Mg/H] is slighly below
solar at z=0.7 and [C/H]=0.1-0.01 at z=2. We detect an associated CIV system at
z=2.7126 in which there is some evidence for the presence of NeVIII, probably
NeVI, NeVII, and possibly SiXII.
