4. Melting and boiling temperatures

In general, when we speak of melting and boiling temperatures, this implies that the reference pressure is atmospheric pressure, so the corresponding temperatures are called normal melting and boiling temperatures. In Tables 1 and 2 of the article are reported as normal melting and boiling temperatures for many inorganic and organic substances. In fact, there is no reliable method for estimating these temperatures.

To obtain a rough value of the melting temperature T _f , a group contribution method has been proposed by Joback for organic substances: $T_{\text{f}}=122+{\displaystyle \sum {\Delta }_{T_{\text{f}}}}$