MELTING POINT
"As to melting points, some in the literature are of plant isolates and other are of synthetic samples. A brief and incomplete survey has revealed the following numbers, all in °C: 44, 44.6-46.8, 46, 47, 48-49, 49-50, 56-57, 57-59, 58-60, 64-67, 67 and 67-68. The 58-60 and 64-67 values are from the Aldrich Chemical Company, for samples bearing the purity claims of "puriss" and 99+% "Gold Label" resp. The Merck Index gives the very early, very low values of 46 °C and 44.6-46.8 °C and claimes that the bp is 60-80 °C with atmospheric pressure being implied. It is clearly in error on both matters. No evidence has been published suggesting polymorphism. The published mp values for the trimethyl quaternary iodide span the range from 188 °C to 233 °C, including in-between values of 197 °C and 216-217 °C. This physical property is of limited value." --Alexander Shulgin from