156 THE NEW WORLD OF SCIENCE 



SOME OF THE RESULTS 



It is possible to pick out only a few of the many scientific 

 and technical problems which met the chemist when the United 

 States entered the war and which increased as chemical warfare 

 became more and more complex, and to show the results 

 achieved. 



Charcoal. The first problem naturally to engage the atten- 

 tion of the army was that of defense. The Germans were 

 using poison gas. And whether we used it or not, it was 

 necessary to protect our men against German gas. This meant 

 gas masks. And while for comfort and efficiency the face 

 piece was very important, for protection the canister was the 

 vital factor. Of the canister, the filler used was really more 

 important than the shape and size of the tin box and even than 

 the method of filling. From the experience of the British Gas 

 Service we knew that charcoal and soda lime were the neces- 

 sary components oi the filler. We needed to know the general 

 requirements of gas mask absorbents, methods of manufacture, 

 methods of filling, methods of testing and how to secure the 

 maximum efficiency for the greatest number of gases. At the 

 close of the work we had learned that the following were some 

 of the necessary properties of a charcoal (not necessarily all). 

 It should have a very high rate of absorption, or a high degree 

 of absorptive capacity. A man, when exercising, breathes 

 about 60 liters of air per minute. This corresponds, when cal- 

 culated on the basis of the regular army canister, to an average 

 linear air velocity of about 80 centimeters per second. This is 

 obviously a very brief interval in which to remove toxic mate- 

 rials from the air. Furthermore, this absorption must be 

 surprisingly complete. The total result is that an absorbent 

 for use in a gas mask must be capable of reducing the concen- 

 tration of gas from say 1000 parts per million to I part per 

 million or less within o.i second. Of equal importance L; the 

 absorptive capacity of the absorbent, and further, that the gases 

 be held firmly by the absorbent. The material used must be of 



