A good place to start, particularily if looking for basic physical data such as boiling and melting points, densities, refractive indexes and solubilities for your labs. Also includes data on thermodynamics, fluid properties, biochemistry, spectroscopy, atomic and nuclear physics, and polymers. From Arizona State University.
Contains an enormous amount of critical data on inorganic and organic compounds, and pure substances. Featuring physical, thermodynamic, mechanical, and other key properties. It is a major reference source used by those involved in chemistry, physics, and engineering.
Data in the WebBook system are organized by chemical species. The WebBook system allows users to search for chemical species by various means. Once the desired species has been identified, the system will display data for the species.