Next  we  have  cholera  attributed  to  lunar  infiueTices^  to
epidetiiiG  ccnstiiutiona   of  the   air,  to   ^une  constitution
medicale  cholerique,'  all  being,  more  or  less,  relics  of  the
ideas    'which  in  the  middle  ages   attributed  epidemics  to
comets,  earthquakes,  volcanoes,  and  sidereal  changes ;  mag-
netism or  electricity  taking  the  place  of  Saturn  or  Mercury
in  the  scheme  of  causation.    The  theory  that  cholera  has  its
origin  in  some  peculiar  constitution  of  the  air  appears  to
have  been  propounded  by  the  French  physician,  Aroga,  who
afterwards  concluded  the  absence  of  ozone  to  be  the  fona  et
origo  vutli,     Faraday  asserted  that  this  absence  of  ozone  is
connected  with  a  state  of  negative  electricity,  which  would
always  be  found  associated  with  chdera.    Herepath,  refining
on  this  theory,  believed  that  in  Asiatic  cholera  the  stomach
is  strongly  electro-negative,  the  gastric  mucous  membrane
secreting  a  free  alkali ;  and  hence  as  a  curative  agency  re-
commended sulphuric  acid.     Others,  again,  have  sought  to
prove   that   epidemics  of  cholera  are   always    preceded  or
accompanied  by  some  extraordinary  meteorological  change,
which  is  indeed  often  the  case.     Thus  Sir  Cruyer  Hunter
states  that  previous  to  the  Egyptian  epidemic  of  1883  there
was  a  still  cloudless  atmosphere,  saturated  air,  and  a  peculicur
yellow  haze  called  by  the  Arabs  el  hawa  d  asfar^  and  it  was
noticed  that  sparrows  deserted  the  locality  where  the  haze
appeared.     Dr.   Kirker's    Egyptian  meteorological  records
nndoubtedly  show  that  in  June,  1883,  in  Egypt,  as  compared
with  thirteen  previous  Junes,  the  mean  barometric  pressure
was  somewhat  below,  and  the  mean  temperature  somewhat
above  the  average.     The  maximum  relative  humidity  was
also  highest,  while  ozone  and  wind  force  were  low.     From


88  CHOLERA.
