AmDec.?Sarm-}  Action  of  Sulphurous  Acid  and  Salts.  627 
gives  an  account  of  the  experiments  he  has  made  to  ascertain  the 
exact  effects  of  pure  sulphite  of  sodium,  and  the  conclusions  he  has 
arrived  at  with  regard  to  the  action  of  this  salt  and  of  sulphurous 
acid.  He  finds  that  the  sulphites  exert  a  distinctly  poisonous  action 
on  both  cold  and  warm-blooded  animals,  but  they  are  so  rapidly 
changed  into  sulphates  that,  unless  very  large  doses  be  given,  a 
sufficient  amount  of  unchanged  salt  is  not  present  to  produce  a  poi- 
sonous effect.  96-5  per  cent,  of  sulphite  of  sodium  given  appears  in 
the  urine  as  sulphate.  When  large  quantities  are  administered, 
85-8  per  cent,  passes  out  in  five  hours — the  maximum  excretion  of 
both  sulphate  and  sulphite  taking  place  in  the  second  and  third 
hour,  but  more  sulphite  being  excreted  in  the  third  hour.  By  the 
fourth  hour,  all  the  sulphite  has  been  converted  into  sulphate.  The 
digestive  disturbance  which  has  been  found  by  some  to  follow  the 
medicinal  use  of  sulphites  is  probably  due  to  the  sulphurous  acid 
set  free  by  the  acid  of  the  stomach. 
In  man,  small  quantities  in  the  air  breathed  (under  -5  per  1,000) 
cause  spasm  of  the  glottis  and  cough  ;  and  prolonged  respiration  ot 
air  containing  a  very  small  proportion  of  the  gas  will  at  times  give 
rise  to  chronic  catarrh  and  inflammation  of  the  respiratory  organs. 
Watery  solutions  of  S02  produce  a  marked  and  extensive  caustic 
effect.  A  solution  of  -5  to  I  per  cent,  causes  excessive  and  extensive 
gastritis,  and  a  5  per  cent,  solution  corrodes  deeply  when  injected 
into  the  stomach  of  animals,  causing  death  in  three  to  five  minutes. 
It  has  distinctly  a  more  marked  effect  than  sulphuric  acid,  of  which 
solutions  of  from  I  to  20  per  cent,  are  not  invariably  fatal  under 
similar  conditions. 
It  is  easy  to  understand  therefore  that,  though  the  sulphites 
themselves  may  be  without  influence  on  the  gastro-intestinal 
mucous  membrane,  the  sulphurous  acid  given  off,  owing  to  decom 
position  in  the  stomach,  may  lead  to  catarrhal  condition,  sickness 
and  diarrhoea.  Bernatzik  noticed  this  effect  after  doses  of  from  15 
to  60  grs.  of  various  sulphites,  and  also  after  solutions  of  sulphurous 
acid,  and  Pfeiffer  himself,  after  taking  only  7^  grains  of  sulphite  of 
sodium,  suffered  from  pain,  discomfort  and  eructations.  Sulphurous 
acid,  like  other  acids,  can  be  shown,  experimentally,  to  interfere 
with  the  action  of  ptyalin  and  trypsin,  but  not  with  that  of  pepsin; 
but  the  sulphites  probably  have  no  other  effect  on  digestion  than 
that  of  interfering  slightly  with  its  rapidity. 
