Used to give details of gases deemed to threaten the UK during the Second World War. When the yellow disc was turned so that the arrow pointed to a gas, the slots revealed the various details about that gas.
chart a yellow disc secured on top of a wider white disc with the ability to turn the yellow disc; various slots have been cut into the yellow disc and are labelled 'properties', 'detection', 'melting or freezing point', 'persistent or non-persistent', 'effects' and 'first aid treatment' -these slots correspond to blocks of writing on the white disc which are only revealed when the slots are over the top of them; around the outer edge of the white disc are the names of various gases (see inscr ); an arrow is printed at the top of the yellow disc
 printed (on yellow inner disc)  printed (around outer edge of white disc)  printed (in various labelled boxes -see desc below)
 PROPERTIES DETECTION WAR GASES KEEP ALERT ALWAYS CARRY YOUR GAS MASK GEORGE PHILIP & SON, LTD., 32 FLEET STREET, E.C.4 Printed in Great Britain EFFECTS FIRST AID TREATMENT  LUNG IRRITANTS [LETHAL AGENTS] : CHLORINE / PHOSGENE / CHLORO-PICRIN BLISTER GASES [DESTRUCTIVE TO TISSUES] : MUSTARD / LEWISITE BLOOD POISONING : ARSINE TEAR GASES [HARASSING AGENTS TEMPORARY RESULTS] : C.A.P. / K.S.K. / B.B.C. NOSE IRRITANTS [HARASSING AGENTS TEMPORARY RESULTS] D.A. / D.M. / D.C.  [various]