III. On melting point

Abstract

The investigation, of which the memoir contains an account, was undertaken in order to determine, with considerable accuracy, the temperature at which certain organic substances pass from the solid to the liquid state. The apparatus, of which an engraving, on a scale of one-fourth, is given below, consists of a bath nearly filled with oil of vitriol. In this is inserted a glass funnel, having on its lower edge six equidistant semicircular cuts of about 5 millims. radius, and, at the end of the neck, four of the same. A thin test-tube, resting freely on the funnel, contains a bath of paraffin oil, in which the thermometer’s bulb is centrally placed; against the bulb, in a little tube separately represented, is fixed the substance whose melting point is to be determined. When the large bath is heated, constrained and regular convection takes place in the liquid; the effect upon the thermometer is such as to cause the mercury to rise with very great steadiness.