Letter from Howard Walter Florey to L T Poole, War Office Says that penicillin is non-toxic and can be used at nearly any concentration - discusses economy of usage - gives comments on experiments with crude filtrate - discusses production of penicillin for use in burns and eye cases - comments on effect of merthiolate on rate of penicillin deterioration - discusses question of censorship of film on penicillin work in North Africa. 30 September 1943