Determining refractive index of minerals; filling for thermometers instead of mercury, usually with a blue or red dye; extraction solvent for oilseed processing. 2.Suitable for HPLC, spectrophotometry, environmental testing 3.n-Hexane is a chief constituent of petroleumether, gasoline, and rubber solvent. It is usedas a solvent for adhesives, vegetable oils,and in organic analysis, and for denaturingalcohol.