Lactometer is a small glass instrument that is used to test the purity of the milk. It works on the principle of specific gravity of milk (Archimede’s Principle). It measures the relative density of milk with respect to water.
To make of lactometer follow the below steps
- Take an empty ball pen refill. It should have a metal point.
- Take a boiling tube and fill it with water.
- Put the refill in with the metallic point inside the water.
- To make the refill stand upright in the water, put a small piece of eraser into the middle refill.
- Label the stage at which the refill is above water with a marker.
- Now drain the boiling water tube, and fill it with milk.
- Place the refill in milk again, and mark the point showing the portion above the milk surface.
- We can also introduce milk water mixture to the water boiling tube and repeat step 8.
- Now we can compare and test whether water is added to the milk or not.