McDougall, Hersh & Scott
Gas detector badge
 A gas detector badge for detecting harmful gases, including a gas sensitive tape positioned behind a front panel, having an indicator window, a reference window and a control window. The control window is provided with a gas filter, whereas the indicator window is open to the atmosphere to permit harmful gas to pass through the indicator window to the gas sensitive tape; the reference window includes a gas impermeable member to protect the tape from the atmosphere. Harmful gases contacting the badge pass through the indicator window and the control window, passing through the latter at a slower rate, to chemically react with the tape to develop color as a measure of the harmful gases in the atmosphere. 
G Y
G01N Y10T
inventional additional
Gerald
Moore