Question

Difference between hydrometer and lactometer

Answer 1

Hydrometer is actually the instrument which is used the measure the specific gravity of  liquid. They are generally made of glass and composed of stem and a bulb which is filled with suitable follow to enable the instrument to flow.

While the lactometer is a type of the hydrometer specifically used for determining the specific gravity of milk.This is used in order to check the purity of the milk.

So basically the lactometer is only used for milk.

Answer 2

Hydrometer is an instrument which is used to measure the relative density of given liquids.

Principle of working -------- Archimedes's principle.

Lactometer is an instrument that is used to measure the relative density of milk as well as it test the purity of milk.
It is a special type of Hydrometer used only for milks

Principle of working : Archimedes's principle.