Colorless transparent viscous liquid. It is sweet, hygroscopic and flammable. Melting point 17.8ºC (18.17ºC, 20ºC). Boiling point 290ºC (decomposition), 263.0ºC (53.2kPa), 240.0ºC (26.6kPa), 167.2ºC (1.33kPa), 153.8ºC (0.665kPa), 125.5ºC (0.133kPa), flash point (open cup) 177ºC, Relative density 1.26362 (20/20ºC), spontaneous combustion point 392.8ºC, refractive index 1.4746, viscosity (20ºC) 1499mPa·s, vapor pressure (100ºC) 26Pa, surface tension (20ºC) 63.4mN/m. Glycerol can be miscible with water and ethanol, and the aqueous solution is neutral. One part glycerol is dissolved in 500 parts ether or 11 parts ethyl acetate. Insoluble in benzene, chloroform, carbon tetrachloride, carbon disulfide, petroleum ether, oil. It can absorb moisture from the air, as well as hydrogen sulfide, hydrogen cyanide and sulfur dioxide. No smell. Pure glycerol placed at a low temperature of 0 ° C can form a glossy rhombic crystal with a melting point of 17.8 ° C, containing a small amount of water that prevents crystallization. The freezing point of glycerol aqueous solution with different concentration (weight) is: 10, -1.6ºC; 30, -9.5ºC; 50,23.0 ° C; 66.7, -46.5ºC; 80, -20.3ºC; 90, -1.6ºC. In nature, glycerol exists widely in animals and plants mainly in the form of glycerides.