It is said Archimpedes made 2 masses of the same weight as the crown one gold one silver, he then filled a large vessel with water to the very brim, and dropped the silver into it. As much water ran out as was equal in bulk to that of the silver sunk in the vessel.
He then took out the mass and poured back the lost quantity of water using a pint measure until the was level with the brim as before. Thus finding the weight silver corresponding to a definite quantity of water.He repeated this with the gold mass but found that much less water was lost.
Finally , filling the vessel again and dropping the crown itself into same quantity of water, he found that more water ran over for the weight, hence reasoning that more water was lost in the case of the Crown than for the mass, he detected the mixing of silver with the gold, and made the theft of the contractor clear for all to see