74 CONTEMPORARY SCIENCE 



rials, must manufacture 40,000,000 respirators a year in 

 order to supply his Austrian, Bulgarian, and Turkish 

 allies, as well as his own army. 



In the British and American armies the respirator must 

 always be carried with the equipment when within 12 

 miles of the front. Between 12 and 5 miles a man may 

 remove the respirator box in order to sleep, but within 5 

 miles he must wear it constantly. Within 2 miles it must 

 be won constantly in the "alert" position (slung and tied 

 in front). When the alarm is given he must get the res- 

 pirator on within six seconds. The American respirator 

 is identical with the British. The French have a fabric 

 mask made in several layers, the inner provided with a 

 nickel salt to stop HCN, then a layer with hexamethy- 

 lenetetramine ; it has no valve and is hot to wear. The 

 French also use a box respirator, consisting of a metal 

 box slung on the back, with a tube connecting to the face 

 mask ; the latter is of good Para rubber and is provided 

 with a valve. One disadvantage of this form is the dan- 

 ger of tearing the single rubber sheet. The German mask 

 now contains no rubber except one washer; the elastics 

 consist of springs inside a fabric, and the mask itself is 

 of leather. It hardens and cracks after being wet, and is 

 too dependent upon being well fitted to the face when 

 made. 



The following compounds have been used by the Ger- 

 mans in gas clouds or in shells : 



1. Allyl-iso-thiocyanate (Allyl mustard oil), C 3 H 5 NCS 

 (shell). 



2. Benzyl bromide, C 6 H 5 CH 2 Br (shell). 



3. Bromo-acetone, CH 2 Br.CO.CH 3 (hand grenades). 



4. Bromated methyl-ethyl-ketone (bromo-ketone), CH 2 - 

 BrCOC 2 H 5 or CH,.CO.CHBr. CH 3 (shell). Dibromo- 

 ketone, CH 3 COCHBr.CH 2 Br (shell). 



5. Bromine, Br 2 (hand grenades). 



6. Chloro-acetone, CH 2 C1.COCH 3 (hand grenades). 



7. Chlorine, C1 2 (cloud). 



