Our  information  as  to  the  amount  of  carbonic  acid,  whether  relative  or
ibsolate,  exhaled  in  morbid  conditions  of  the  body,  is  very  imperfect.  The
Rsearches  of  Nysten  seem  to  lead  to  the  following  conclusions :

"1.  In  chronic  diseases,  without  fever  or  pulmonary  disorder,  the  chemical
piienoinena  of  respiration  differ  but  little  from  those  of  normal  condition.
''2.  The  air  expired  in  severe  continued  fevers  sometimes  appears  to  contain  a
digbtl/.increased  proportion  of  carbonic  acid;  but  new  experiments  are  required
to  determine  whether  this  is  a  constant  or  an  accidental  occurrence.
**^.  In  certain  diseases  the  expired  air  contains  an  unusually  small  proportion  of
arbooic  acid ;  this  is  especially  the  case  in  severe  dyspnoea,  whether  this  result
^  degeneration  of  the  tissue  of  the  lungs,  or  from  hydrothorax,  ascites,  or  other
cuttes  interfering  with  their  due  expansion.**  (pp.  35-6.)

The  well-known  observations  of  Macgregor,  relative  to  the  decided  in-
ci^ease  in  the  amount  of  carbonic  acid  exhaled  from  the  lungs  during  the
^fttte  stage  of  smallpox,  measles,  and  scarlatina,  and  upon  the  augmenta-
^  which  was  presented  in  a  fatal  case  of  extensive  icthyosis,  are  well
bown ;  but  we  think  it  doubtful  whether  this  increase  was  due  to  an
^Wlnte  increase  in  the  quantity  of  carbonic  acid  exhaled,  or  whether  it
^  not  rather  referrible  to  the  stoppage  of  the  cutaneous  respiration,
rtidi  would  throw  more  work  upon  the  lungs.
We  have  now  to  notice  the  researches  of  Dr.  Hannover,  which  were
Cttried  on  in  conjunction  with  Professor  Scharling.  We  hope  that  these
^  to  be  taken  but  as  an  earnest  of  more  extended  observations ;  since  at
pMent  the  amount  of  information  contributed  by  them  is  very  limited.
