264 
Methods  of  Gas  Warfare. 
Am.  Tour.  Pharm. 
April,  1 918. 
effective  at  the  time,  but  provision  was  made  to  meet  increased  con- 
centration of  phosgene.  We  never  had  any  actual  evidence  during 
the  attack  that  phosgene  was  being  used,  as  no  samples  were  actually 
taken  from  the  cloud,  but  cylinders  of  phosgene  were  captured  later. 
Glass  vacuum  tubes,  about  10  by  30  Cm.,  with  a  tip  that  could  be 
broken  off  and  then  closed  by  a  plasticine-lined  glass  cap,  were  dis- 
tributed, but  the  only  one  that  came  back  was  an  unopened  tube 
found  in  a  hedge,  and  marked  by  the  finder  "  Dangerous ;  may  con- 
tain cholera  germs."  In  a  gas  attack  everybody  keeps  quiet  or  else 
has  a  job  on  hand,  and  conditions  are  not  conducive  to  the  taking 
of  gas  samples.  The  original  types  of  vacuum  tube  were  smaller 
than  those  now  used. 
There  was  a  long  search  for  materials  that  would  absorb  phos- 
gene, as  there  are  few  substances  that  react  readily  with  it.  The 
successful  suggestion  came  from  Russia.  The  substance  now  used 
very  extensively  by  all  is  hexamethylenetetramine  (urotropine) 
(CH2)6N4,  which  reacts  very  rapidly  with  phosgene.  Used  in  con- 
junction with  sodium  phenate,  it  will  protect  against  phosgene  at  a 
concentration  of  1 : 1,000  for  a  considerable  period.  An  excess  of 
sodium  hydroxide  is  used  with  the  sodium  phenate,  and  a  valve  is 
provided  in  the  helmet  for  the  escape  of  exhaled  air.  The  valve 
was  originally  devised  so  that  the  hydroxide  would  not  be  too  rap- 
idly carbonated,  but  it  was  found  in  addition  that  there  is  a  great 
difference  in  ease  of  breathing  and  comfort  if  a  valve  is  placed  in 
the  mask.  The  helmet  is  put  on  over  the  head,  grasped  with  left 
hand  around  the  neck  and  tucked  into  the  jacket.  This  form  is 
still  used  in  reserve. 
By  this  time  gas  shells  were  beginning  to  be  used  in  large  num- 
bers, and  it  became  evident  that  protection  by  a  fabric  could  not  be 
depended  on  with  certainty.  The  box  type  of  respirator  was  the 
next  development.  Respirators  have  to  fulfill  two  requirements 
which  are  quite  opposed  to  one  another.  In  the  first  place  they 
should  be  sufficiently  large  and  elaborate  to  give  full  protection 
against  any  concentration  of  any  gas,  whereas  military  exigency 
requires  that  they  be  light  and  comfortable.  It  is  necessary  to 
strike  a  balance  between  these  two.  Upon  a  proper  balance  de- 
pends the  usefulness  of  the  respirator.  Oxygen  apparatus  will  not 
do  on  account  of  its  weight  and  its  limited  life.  Two  hours'  life 
is  excessive  for  that  type.  The  side  that  can  first  force  the  other 
to  use  oxygen  respirators  for  protection  has  probably  won  the  war. 
