Mohr-Westphalian balance

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Experimental setup:
A: weights, B: glass floats , C:  adjusting screws for horizontal alignment, D: salt to dissolve in water

The Mohr-Westphalsche balance (after Karl Friedrich Mohr ) is a unequal arm lever balance for determining the density of liquids .

The static buoyancy experienced by a body that is immersed in the liquid is proportional to the mass of the amount of liquid displaced. From this, if the volume of the body is known, the density of the liquid can be deduced ( Archimedes principle ).

The balance is designed and calibrated in such a way that the density of the liquid can be read off directly in decimal format. For this purpose there are 10  notches on the load arm , into which weights are attached until the balance is in equilibrium. Now read from the heaviest to the lightest, with the number of the notch indicating the number of the respective digit of the density.