An instrument for testing the purity of the air, or rather the quantity of oxygen it contains.

An instrument for measuring concentrations of gaseous or dissolved oxygen; a eudiometer.

An instrument or device for measuring the amount of ozone in the air.

An instrument or device for detecting ozone.

An instrument for detecting septic matter in the atmospheric air.

An instrument for estimating the concentration of dust in the air by observing the depth of colour in a sample of the air when it is expanded into a…

see quot.

A kind of impinger in which a known volume of air is directed on to a slide coated with a substance to which any dust particles will adhere.

an instrument that makes use of the Tyndall effect for measuring aerosols and suspensions.