Xylene ("xylol" is archaic) is a mixture of isomers - ortho, meta, and para 
xylenes, with some ethylbenzene. If you don't understand this statement, look 
up:

Conventional structural formulas:
http://www.mgc.co.jp/eng/aromatic/xylen/index.shtml

Atomic models:
http://www.mgc.co.jp/eng/aromatic/index.shtml

That's why containers are usually labeled "xylenes" - there are three or four 
closely related chemical compounds that bear this name.

Clearly people have had problems with contaminents in cheap xylenes. Does 
anyone know what the chemical specifications are for xylene for histologic 
purposes? I imagine Dick Dapson knows, but "xylene" is a four-plus-two letter 
word around Anatech, for reasons we all know (or jolly well should know).

Bob Richmond
Samurai Pathologist
Knoxville TN