Galinstan oral thermometer. Galinstan is a eutectic alloy of gallium, indium, and tin (stannum in Latin). It is a liquid at room temperature. Galinstan is non-toxic and is often used in many applications as a replacement for toxic liquid mercury. For example, thermometers that use galinstan instead of mercury are available, as shown here. Note the two temperature scales, in degrees Celsius and in degrees Fahrenheit.