ADAugu"t'  mT™' }  Physiological  Characteristics  of  Acetylene.  365 
and  accordingly  declared  acetylene  a  poison.  Moreover,  it  seemed 
to  exercise  the  action  of  a  direct  poison  on  animals. 
This  was  ascertained  before  acetylene  was  regularly  produced 
from  carbide.  The  acetylene  of  that  date  was  made  by  the  incom- 
plete combustion  of  coal-gas,  whence  more  or  less  carbon  monoxide 
was  present  in  the  acetylene  obtained,  thus  accounting  for  some 
degree  of  toxic  action  of  the  acetylene  examined.  Carbon  monoxide 
is  the  poison  of  common  illuminating  gas. 
With  the  discovery  of  carbide  and  its  use  for  the  production  of 
acetylene,  all  of  this  has  been  changed,  it  is  now  found  that  acety- 
lene from  carbide  does  not  contain  carbon  monoxide,  that  it  does 
not  have  the  property  of  fixing  haemoglobin,  and  that  it  does  not 
rob  the  blood  of  its  capacity  to  take  up  oxygen  from  the  air  and 
carry  it  into  the  tissues.  Hence  the  old  allegation  that  acetylene 
is  a  poison  because  it  deprives  the  blood  of  its  oxygen-carrying 
capacity  is  no  longer  justified. 
Another  poisonous  product  sometimes  present  in  the  acetylene 
made  by  the  old  combustion  process  was  hydrocyanic  acid.  Never 
in  large  quantities,  it  yet  is  so  toxic  that  we  can  fully  appreciate  its 
effect.  It  is  not  present  in  the  carbide  acetylene  and  so  may  be 
dismissed  from  consideration.  Another  charge  that  is  no  longer 
justified  is  that  acetylene  is  a  poison  because  of  the  presence  of 
phosphine  as  an  impurity.  This  forms  when  carbide  is  made  from 
limestone  containing  phosphate,  which  is  reduced  by  the  action  of 
the  coke.  The  selection  of  limestone  free  from  phosphate  has  prac- 
tically obviated  this  impurity  and  any  poisonous  effect  of  the  acetylene 
consequent  thereto.  Indeed,  the  present  day  product  may  be  said 
to  avoid  the  pitfalls  of  impurities  so  that  its  effect  is  determined 
by  the  characteristics  of  acetylene  itself.  We  may  consider  then 
whether  acetylene,  as  such,  is  or  is  not  a  direct  poison. 
My  present  observations  have  been  directed  to  the  inquiry  whether 
it  produced  noticeable  effect  on  human  subjects  when  present  in 
increasing  amounts  up  to  2^2  per  cent,  during  a  period  of  2^  hours. 
To  this  end,  four  men,  including  myself,  were  enclosed  in  a  room 
of  about  800  cu.  ft.  capacity ;  at  the  beginning  and  four  times 
subsequently  at  intervals  of  a  half -hour,  acetylene  was  liberated  in 
the  room  bv  throwing-  450  grams  of  carbide  into  an  open  tub  of 
water,  this  corresponding  to  the  liberation  of  4  cu.  ft.  of  acetylene 
each  time;  that  is,  20  cu.  ft.  in  all,  2T/2  per  cent,  of  the  capacity  of  the 
room. 
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