Tributes 



bearing on the medical aspects of this new form of warfare. Naturally 

 much attention was given at first to the effects of such gases as chlorine, 

 the first gas to be used for offensive purposes, which is highly irritant 

 to the lungs and provokes acute pulmonary oedema. But in addition 

 many other poisonous gases, which might or actually did serve as 

 effective offensive agents, had to be investigated. 



Let me quote but one instance to show the strength of Barcroft's 

 scientific convictions and his personal courage. Hydrocyanic acid was 

 naturally suggested as an offensive agent, but although it was actually 

 employed in the field in the earlier days of gas warfare its effectiveness 

 was uncertain. Tests on different animals of the toxicity by inhalation 

 of this poison showed that there was a surprising difference of suscepti- 

 bility in different species, the dog being particularly sensitive and the 

 guinea-pig, goat and monkey being very much less sensitive. If, 

 therefore, an assessment of the toxicity were to be based solely on 

 experiments on a highly susceptible animal a false impression of the 

 toxicity to man might be gained. Barcroft, feeling convinced that man 

 must be much less susceptible than the dog, decided to settle this point. 

 He therefore went, unprotected by any respirator, into a respiration 

 chamber with a twelve-kilogram dog and released into the air in the 

 chamber enough gaseous hydrocyanic acid to give a concentration of 

 about one part in two thousand. In just over one minute the dog 

 was unconscious, and at the end of one and a half minutes was in con- 

 vulsions and appeared to be in extremis, when Barcroft left the chamber 

 having felt neither breathlessness nor any symptoms. Directly after- 

 wards the dog was pulled out apparently dead, but although the 

 ' corpse ' was put aside for burial it was found walking about the next 

 morning. But Barcroft had proved his point and shown conclusively 

 that the toxicity of hydrocyanic acid to man was not nearly so great 

 as is commonly supposed, and he thus prevented further futile efforts 

 to use hydrocyanic acid as a chemical warfare agent. 



I was myself serving in France in the R.A.M.C. during all this period, 

 being seconded to the Directorate of Gas Services as Physiological 

 Adviser, and Barcroft visited us a number of times for discussions 

 about current problems or to take part in inter-Allied conferences in 

 Paris on gas warfare. I have very happy memories of those visits, for 

 the vigour and activity of his mind, his keen anxiety to appreciate the 

 problems as we saw them in the field, the acuteness of his suggestions 

 and his readiness at all times to help were a real stimulus to us all. 



One recollection I have, of a rather different kind, which stands out 

 in my memory. On one of his earlier visits I was ordered to show him 

 something of conditions nearer the line. So, among other places, I 

 took him to an advanced dressing station in the vicinity of Loos. This 



15 



