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Slip melting point

Slip melting point

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The Slip melting point or "slip point" is one conventional definition of the melting point
Melting point
The melting point of a solid 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 standard atmospheric pressure...

 of a wax
Wax
thumb|right|[[Cetyl palmitate]], a typical wax ester.Wax refers to a class of chemical compounds that are plastic near ambient temperatures. Characteristically, they melt above 45 °C to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, nonpolar solvents...

y solid
Solid
Solid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...

. It is determined by casting a 10 mm column of the solid in a glass tube with an internal diameter of about 1 mm and a length of about 80 mm, and then
immersing it in a temperature-controlled water bath
Water bath
A water bath can refer to:* A Bain-marie* A heated bath* A Laboratory water bath...

. The slip point is
the temperature at which the column of the solid begins to rise in the tube
due to buoyancy
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

, and because the outside surface of the solid is molten.

This is a popular method for fats and waxes, because they tend to be mixtures of compounds with a range of molecular mass
Molecular mass
The molecular mass of a substance is the mass of one molecule of that substance, in unified atomic mass unit u...

es, without well-defined melting points.