The Melting Mechanism of the Alkali Thiocyanates

where Ws and WL represent the number of independent ways of realizing the arrangements of solid and melt respectively and Sf is the entropy of fusion. Each new kind of disorder which occurs on passing from the crystal to the melt involves a new mechanism of randomization on melting. Ubbelohde! has summarized the different ways of randomization in the transition from the solid to the melt as positional, orientational, vibrational and configurational randomization. Other terms, which in certain cases can make large contributions to the entropy of fusion, are those due to the presence of mesomorphic states and the formation of association complexes in the melt2. Treating these increases of disorder as independent and additive, Sf becomes to a first approximation: