222 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1919. 
siles or shell fragments which armor like this would have stopped. 
The Germans made much use of body armor, and our own Govern- 
ment went to the great art galleries for specialists in armor in its 
effort to produce helmets affording the utmost measure of protection. 
Our highest ambition was to rival the product of the best armorers 
of the Middle Ages, over whom we had a great advantage in the 
superior qualities of modern special steels. Steel containing much 
manganese was found best adapted to use in helmets and was used 
also in the British helmet. Of 7,000,000 helmets ordered we received 
2,700,000. It is curious to note in passing that fine sawdust played 
an important part in their production, the helmets, after being first 
painted, receiving, while the paint was wet, a coat of sawdust from 
a blower, after which the dried and roughened surface received a sec- 
ond coat of paint. The purpose of this treatment was, of course, to 
break up and dissipate reflected light. 
Perhaps the most striking offensive development of the war was 
the employment of toxic gases and latterly of toxic smokes. These 
gases were of many sorts, but chlorine was the one first used by the 
Germans in their attack in the Ypres salient in April, 1915, and this 
was so disastrous in its effect that had it been followed up, the Ger- 
mans could undoubtedly have gone through to the coast with prac- 
tically no opposition. The Germans in their earlier attacks dis- 
charged the gas from great numbers of cylinders placed within the 
trenches, and the direction and velocity of the wind determined the 
possibility of a gas attack. Both the Germans and the Allies, there- 
fore, quickly resorted to the use of gas in shells, while the Allies de- 
veloped the extremely effective Livens projector, which, firing simul- 
taneously sometimes to the number of hundreds, discharged upon a 
localized area gas-filled drums about 24 inches long and 8 inches in 
diameter. Their effective range was about a mile. Much gas was also 
thrown in hand grenades. 
Field experience and the conditions imposed by quantity produc- 
tion soon narrowed the number of available gases to relatively few, 
and of these phosgene was one of the most toxic. Certain thermo- 
chemical considerations led to an ingenious modification of. the 
method of production, and phosgene was produced in great amounts 
by passing a mixture of oxygen and carbon dioxide over hot coke 
in gas producers and thereafter sending the carbon monoxide thus 
formed through catalyzers, together with chlorine. which, combining 
with the carbon monoxide, produced phosgene. 
The chief seat of poison-gas manufacture in this country, though 
its production was largely supplemented elsewhere, was Edgewood 
Arsenal, which, producing its chlorine by the electrolysis of a solu- 
tion of common salt, had a phosgene capacity of 20 tons a day. 
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