Gas enters vessel 3 through pipe 1 and air enters vessel 4 through pipe 2. After filling the vessels, both gases flow out through narrow holes a and b at the same pressure. The more vessel 4 descends to the moment when vessel 3 is empty, the greater the density of the gas being investigated. The amount of descent of vessel 4 is registered by recording device 5 on graph paper strip 6 and serves as a measure of density of the investigated gas.
$3728$SHP,M$