We use molecular sieves in our Pap stain clearing-xylenes to keep them
water-free.  Coupled with keeping the preceding alcohol dye-free so it does
not color the xylene and daily filtration of all xylene baths to keep them
particulate-free, we no longer discard or recycle xylene by distillation.
Like the Energizer bunny, the xylene keeps on going indefinitely -- thereby
saving significant dollars annually.  Obviously, this technique is not
applicable to paraffin-contaminated xylene.

Gary W. Gill