This quantity can take on negative values when transverse motions shorten rigid metal-anion bonds in the so-called “guitar string” effect. Methods for measuring this quantity include zero force TMA and dilatometry with vitreous silica push-rods. This quantity is negative for scandium trifluoride and zirconium tungstate. For many materials, this quantity is inversely proportional to melting temperature. Precision mechanical systems, especially opto-mechanical systems, require materials with a low value for this quantity, such as the iron-nickel alloy Invar. For isotropic materials, (-5[1])multiplying the linear form of this quantity by three gives its volumetric form. For ideal gasses, the volumetric form of this quantity equals one over temperature. For 10 points, name this quantity denoted alpha that relates changes in size to changes in temperature. (10[1])■END■