Fusibility, that property by which solid bodies are rendered liquid by the application of heat. It is probably possessed by all bodies, but some are so altered by chemical changes among their own elements or by the action of external bodies in contact, that they cease to retain their individual characteristics before their melting point is reached. Although it seems that in some crystalline organic com-pounds, and also in some of the fats, the fusing point varies after the body has been once melted, it is generally the case that the fusion takes place at a constant temperature for the same body, that this point is ascertained for many, and is given with each as one of the distinctive qualities. Carbon, however, resists this determination, and the assertions of its fusibility made by some experimenters arc not generally admitted as establishing the fact. The range of the fusing point of bodies is very great, some existing in the solid state only far below the ordinary temperatures, while others require the most intense artificial heat to cause them to assume the liquid form.

This is exhibited in the following table, which comprises many of the bodies thus arranged by Pouillet:

The fusing point of oils, etc, is ascertained by introducing them together with a fine thermometer into small glass tubes, and placing these in water, which is gradually heated till the substances melt. The thermometer indicates the temperature. The method of determining the high melting points of the metals, etc, will be described in the article Pyrometee.