562 
Effect  of  Noxious  Gases. 
Am.  Jour.  Phara  . 
Dec,  1893. 
me,  in  grouping  the"  results  obtained  in  experiments  with  Carbon 
Dioxide,  Carbonic  Oxide  and  Sulphureted  Hydrogen  on  animal  life, 
the  medical  fraternity  will  at  least  have  a  condensation  of  experi- 
ments for  reference,  from  many  authorities  combined  with  the 
results  of  my  own  experiments.  I  claim  that  my  experiments  are 
absolutely  accurate,  as  the  means  employed  for  mixing  the  different 
atmospheres  (the  Shaw  Gas  Tester)  is  acknowledged  to  be  as  nearly 
perfect  as  human  agency  can  make  anything,  and  has  been  awarded 
the  Elliott  Cresson  and  Scott  Legacy  Medals  for  accuracy — the 
highest  awards  in  the  gift  of  the  Franklin  Institute,  and  is  to  gases 
what  weights  and  scales  are  to  solids. 
It  is  not  my  intention  to  go  into  the  constituents  of  the  above 
gases,  there  being  no  necessity  for  my  doing  so  in  this  paper.  I 
have  simply  one  object  in  view,  to  describe  the  effect  produced  by  them 
on  animal  life,  the  result  of  recent  experiments.  The  Shaw  Gas 
Tester,  which  I  used  for  mixing  my  gases  in  the  centesimal  propor- 
tions desired,  is  an  apparatus  simple,  convenient  and  accurate,  con- 
sisting of  2  pumps  with  pistons  attached  to  a  graduated  arm,  so  that 
one  cylinder  can  be  set  to  pump  10  per  cent,  of  gas  and  the  other  90 
per  cent,  of  air — or  vice  versa ;  or  any  per  cent,  to  the  lowest  fraction. 
It  is  the  only  instrument  in  the  world  capable  of  mixing  gases 
accurately,  rapidly,  and  continuously  in  any  per  cent,  desired,  the 
product  of  the  two  cylinders  being  forced  through  an  ejector  or 
mixer  before  delivery. 
The  animal  under  treatment  is  placed  in  a  bell-shaped  glass 
cylinder  16  inches  high,  4  inches  diameter  at  neck  and  8  inches  at 
base.  The  cylinder  is  placed  horizontally  on  the  table,  with  the 
neck  towards  the  operator,  and  is  connected  with  the  instrument,  at 
the  neck,  by  means  of  a  rubber  tube.  The  animal  rests  on  all  fours 
facing  the  operator  with  its  nose  near  the  aperture  through  which 
the  gases  enter  to  the  cylinder  from  the  instrument  or  mixer. 
The  end  of  the  bell-shaped  glass  cylinder  is  entirely  open  to  the 
air  so  that  the  mixture  of  gas  and  air  is  discharged  and  replaced 
every  4  seconds  by  each  stroke  of  the  pump,  always  maintaining  a 
constant  mixture,  preventing  stratification,  or  contamination  through 
the  exhalations  of  the  subject.  The  cylinder  being  of  glass  and 
perfectly  transparent,  enables  the  operator  to  observe  every  change 
in  the  condition  of  the  animal. 
The  difference  in  results  obtained  by  the  various  authorities  has 
