364  Physiological  Characteristics  of  Acetylene.  jA^uJg°ust'  iP9Hrm* 
years  of  careful  study  were  needed  to  solve  the  last  of  the  dangers 
involved  in  the  use  of  kerosene,  while  the  difficulties  connected 
with  illuminating  gas  and  electricity  are  still  with  us.  This  paper 
will  be  limited  to  the  problems  of  adjustment  presented  by  the  use  of 
acetylene  as  an  illuminant. 
This  leads  us  at  once  to  the  inquiry,  Is  acetylene  a  direct  poison? 
The  answer  is  no.  This  question  is  asked  with  some  seriousness, 
however,  because,  on  the  one  hand,  of  the  notoriously  toxic  action 
of  common  illuminating  gas,  due  to  the  carbon  monoxide  which 
enters  so  largely  into  its  composition,  by  reason  of  which  the  mind 
of  the  inquirer  is  already  not  only  prepared  to  believe  that  acety- 
lene is  poisonous,  but,  in  fact,  in  some  instances  has  that  idea  rigidly 
implanted  there.  It  is  further  asked  with  seriousness,  because,  in 
the  literature  of  the  subject, -we  find  some  views  that  it  is  poisonous. 
Early  writers  declared  that  it  combined  with  the  blood  and  had 
a  marked  poisonous  effect,  like  carbon  monoxide. 
Any  gas,  when  it  replaces  air,  if  incapable  of  supporting  respira- 
tion, is  injurious  and  even  fatal,  not  because  it  is  poisonous  but 
because  it  deprives  the  body  of  oxygen.  Because  of  this,  acetylene 
is  capable  of  doing  injury.  If  it  accumulates  in  some  small,  unventi- 
lated  space,  like  the  cabin  of  a  boat,  it  is  entirely  capable  of  shutting 
off  the  supply  of  air,  of  preventing  respiration  and  hence  causing 
harm  and  even  death.  It  suffocates  because  it  is  incapable  of 
supplying  oxygen,  without  which  man  cannot  live. 
When  acting  in  this  way,  acetylene  is  not  a  direct  poison ;  it  does 
not  do  anything  to  the  body  to  injure  it.  It  does  harm  only  in- 
directly, by  withholding  air.  The  recognition,  then,  of  injury  by 
suffocation  throws  no  light  on  our  inquiry  whether  it  is  a  direct 
poison.  The  presence  of  common  illuminating  gas  in  air,  even 
to  the  amount  of  a  fraction  of  a  per  cent.,  is  distinctly  injurious 
and  may  even  be  fatal,  though  such  air  contain  an  abundance  of 
oxygen.  The  carbon  monoxide  contained  in  illuminating  gas  enters 
the  blood  through  the  lungs  and  attaches  itself  strongly  to  the  color- 
ing matter  of  the  blood,  rendering  it  incapable  of  taking  up  the 
oxygen  of  air  though  the  air  contain  oxygen  in  ample  amount.  Thus 
death  supervenes  not  because  the  body  is  denied  oxygen  but  because, 
through  the  fixation  of  the  coloring  matter  of  the  blood,  it  has  lost 
its  capacity  to  use  oxygen.  Has  acetylene  this  or  any  other  directly 
poisonous  action?  Some  early  observers  said  it  had.  They  found 
fixation  of  haemoglobin  quite  similar  to  that  of  carbon  monoxide 
