In a pathology laboratory, paraffin wax is used to impregnate tissue prior to sectioning thin samples of tissue.

Water is removed from tissue through ascending strengths of alcohol (75% to absolute) and the tissue is cleared in an organic solvent such as xylene.  

The tissue is then placed in paraffin wax for a number of hours and then set in a mold with wax to cool and solidify; sections are cut then on a micro tome

Paraffin wax was first produced commercially in 1867, less than 10 years after the first petroleum well was drilled. Paraffin wax precipitates readily from petroleum on chilling. Technical progress has served only to make the separations and filtration more efficient and economical.  

Purification methods consist of chemical treatment, decolorization by adsorbents, and fractionation of the separated waxes into grades by distillation, recrystallization, or both. Crude oils differ widely in wax content.