Question

what is meant by beckmenn thermometer

Answer 1

Definition of Beckmann thermometer. : a very sensitive thermometer that has a small range adjustable for any desired values and that is used for determining accurately small differences in temperature (such as the change in freezing point or boiling point of a liquid when some substance is dissolved in it)

Answer 2

A Beckmann thermometer is a device used to measure small differences of temperature, but not absolute temperature values. It was invented by Ernst Otto Beckmann, a German chemist, for his measurements of colligative properties in 1905. Wikipedia