Immagini

DESCRIPTION

Exhibit 377 is a Mohr-Westphal balance, a simple and compact hydrostatic balance used to determine the density of liquid and solid substances.
It is constituted by a yoke with asymmetric arms: the shorter arm carries a counterweight whose position can be modified with a screw; the longer arm carries a glass cylinder when measuring liquid densities. In air this cylinder is balanced by the counterweight.
There are 10 marks inscribed at equal separation on the long arm for positioning different rider weights. When the cylinder is immersed in the liquid being examined, the hydrostatic pressure is balanced by the value and position of the rider weights.
If the balance is not calibrated, it is necessary determine the hydrostatic pressure using distilled water at 4 degrees Centigrade: the absolute density of the other liquid is determined comparing the weights necessary to rebalance with distilled water and with the liquid of unknown density.

By using the known density of some liquid one can also determine the density of a solid body, measuring its volume and the hydrostatic pressure exerted on it when immersed in this liquid.

Dati Catalografici