Very interesting, thanks Joe for the link. This ties in with a book I just purchased and received, titled The First World War As I Saw It by Percy L Kingsley. After surviving Vimy Ridge with the 5th Batt. Kingsley became CSM of the 1st Canadian Div Gas School in Oct. 1917. He has some very detailed and invaluable descriptions of all the various gases (7) used in WW1 complete with how they "smelled" and comments on their effectiveness in various atmospheric conditions. According to "King" as he was called in the trenches, the Brit Box Respirator was far superior to the German gas mask. I am going to ask for permission to publish the full Kingsley account from his memoirs about the Gas School which amounts to approx 3 pages on the use of poison gases in . I love reading the memoires of WW1 veterans and this one was unique.