Issue 269 is up!
Science Masterclass. A sleuth identifies the instant poison used for a fiendish crime: '...CO2 gas. Carbon dioxide, you know.' [...] 'Are you sure?' 'Positive! As both you gentlemen know, it is a violent and fatal poison. When inhaled in any quantity, as for example from a vial, it produces a spasm of the glottis and immediate death.' (George Allan England, 'Ping-Pong', in Best Detective Stories, 1930) [MP]