(Gr. 65, well, 7riwv, fat), a hydrocarbon of the paraffin series, probably a pentane, C 5 H 12, discovered by K. Reichenbach in wood-tar. It is also formed in the destructive distillation of many substances, as wood, coal, caoutchouc, bones, resin and the fixed oils. It is a colourless highly volatile and inflammable liquid, having at 20° C. a specific gravity of 0.65.