A  januarryPXm'}         Modern  Surgical  Dressings.  29 
of  salts  was  the  medium  used  in  the  transmission  of  electrical 
energy. 
Oxygen  gas  when  under  pressure  had  a  germicidal  effect,  espe- 
cially so  when  the  bacteria  were  in  a  moist  state.  Nascent  oxygen 
was  found  to  be  a  powerful  germicide.  Ozone  gave  similar  results, 
as  did  oxygen.  Carbon  dioxide  was  found  to  be  an  inhabitant, 
but  not  a  germicide.  The  gaseous  oxides  of  nitrogen,  except 
N20  were  found  to  be  powerful  in  their  action  upon  bacteria,  but 
destructive  to  dressing  material  and  productive  of  great  irritation 
upon  inhalation.  Sulphur  dioxide  was  found  to  be  germicidal  in 
the  presence  of  moisture,  but  inapplicable  to  many  classes  of  the 
materials  used  in  surgical  dressings.  Chlorine  gas  is  a  disinfectant, 
especially  in  its  reactions  which  takes  place  in  the  bleaching  pro- 
cess, namely,  union  with  hydrogen,  and  consequent  liberation  of 
oxygen. 
The  bleaching  process,  therefore,  effectually  destroys  germ  life. 
Iodine  and  bromine  are  energetic  agents  in  the  presence  of  mois- 
ture, but  they  react  destructively  with  materials  used  in  surgical 
dressings.  Formaldehyde  vapors  possess  a  high  power  as  a  germi- 
cide. The  vapors  are  highly  irritating  and  destructive  to  flesh 
tissue.  They  are,  however,  applicable  in  the  disinfection  of  some 
classes  of  material  used  in  dressings,  and  are  utilized  in  the  pro- 
cesses hereinafter  outlined. 
During  the  mechanical  process  of  carding  cotton  and  other 
fibres,  the  fibres  are  subjected  to  prolonged  friction,  with  conse- 
quent heat  and  electrical  action.  The  results  upon  infected  fibre 
passed  through  the  process  were  interesting,  and  the  process  was 
found  to  be  one  of  sterilization. 
Experiments  numbering  many  hundreds  of  series  were  made  to 
ascertain  the  value  of  pressure  as  a  sterilizing  agent  upon  dress- 
ing materials.  The  results  show  that  infected  fibres  may  be  steril- 
ized by  a  pressure  of  50  to  100  tons  to  the  square  inch.  This  pro- 
cess has  been  utilized  in  the  sterilization  of  certain  forms  of  surgi- 
cal dressings. 
With  the  discovery  of  a  new  species  of  bacteria  there  is  said  to 
be  a  new  chemical  born  for  its  destruction. 
But  in  the  present  day  practice  of  surgery,  only  in  a  few 
instances,  may  we  use  chemical  germicides  for  the  disinfection  of 
dressings  and  allow  the  chemical  to  remain  in  the  finished  pro- 
