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A melting-point apparatus is a scientific instrument used to determine the melting point of a substance. Some types of melting-point apparatuses include the Thiele tube , Fisher-Johns apparatus, Gallenkamp (Electronic) melting-point apparatus and automatic melting-point apparatus.
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa.
During heating, the point at which melting is observed and the temperature constant is the melting point of the sample. [1] A more modern method uses dedicated equipment, known as a melting point apparatus. A slow heating rate at the melting point is needed in order to get an accurate measurement.
This melting-point apparatus for use with a microscope was developed by the Austrian pharmacognosist Ludwig Kofler (30 November 1891 Dornbirn - 23 August 1951 Innsbruck) and his wife mineralogist Adelheid Kofler. In 1936, the Koflers and Mayrhofer published their "Mikroskopische Methoden in der Mikrochemie" [Kofler, L., A.
cloud point (nonionic surfactants) hardness; melting point; solids or dissolved solids; salinity; specific gravity; density; turbidity; viscosity; moisture (Karl Fischer titration) Wet chemistry is also used in environmental chemistry settings to determine the current state of the environment. It is used to test: [citation needed] Biochemical ...
The Fisher-Johns apparatus was developed by Fisher Scientific. It consists of a rheostat controlling the heating mantle and a horizontally placed thermometer. To test a materials melting point, a glass or plastic coverslip is placed over the heating mantle, a sample of the material of rice grain size or slightly smaller is then placed on the ...
The apparatus is heated. Dissolved gases evolve from the sample first, and the air in the capillary tube expands. Once the sample starts to boil, heating is stopped, and the temperature starts to fall. The temperature at which the liquid sample is sucked into the sealed capillary is the boiling point of the sample. [1] [2] [3] [4]
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