438 
PRODUCTION  OF  NITRE  IN  INDIA. 
nary  household  use  ;  even  the  locomotives  on  some  South  Ameri- 
can lines  had  to  be  supplied  with  distilled  water,  to  avoid  the 
formation  of  saline  crusts  in  the  boilers. 
Dr.  J.  H.  Gilbert  was  led  to  believe  that  the  process  of  nitri- 
fication was  practically  independent  of  the  oxidation  of  atmos- 
pheric nitrogen  or  of  electrical  action  ;  some  years  ago  he 
searched  for  ammonia  and  nitric  acid  in  rain  water  which  fell 
during  a  heavy  thunderstorm,  and  found  ammonia  without  diffi- 
culty, but  the  quantity  of  nitric  acid  was  excessively  small. 
Mr.  John  Williams  took  occasion  to  examine  for  sulphuric  acid 
and  ammonia  in  the  rain  water  which  fell  during  the  thunder- 
storm in  London  about  the  end  of  May.  The  Nessler  test  im- 
mediately indicated  the  presence  of  ammonia,  and  the  amount  of 
sulphuric  acid  was  by  no  means  inconsiderable. 
Dr.  Hugo  Muller  said  it  was  well  known  that  organic  matter 
containing  but  little  nitrogen  furnished  nitrate  as  the  result  of 
its  putrescence,  and  it  had  been  hinted  that  the  oxidation  of  these 
organic  matters  was  capable  of  inducing  (by  a  sort  of  catalytic 
action)  the  formation  of  nitric  acid  from  the  surrounding  atmos- 
pheric nitrogen.  Schonbien  proved  that  nitric  acid  was  formed 
merely  by  bringing  nitrogen  gas  in  contact  with  flame. 
Dr.  Guthrie  was  desirous  of  assuring  himself  that  the  proceeds 
of  the  sale  of  nitre  more  than  covered  the  cost  of  production  un- 
der favorable  circumstances  of  native  labor.  Some  years  ago  he 
proposed  to  the  Government  authorities  to  collect  saltpetre  in 
the  Mauritius,  for  the  town  lies  low  and  near  the  sea,  and  there 
were  difficulties  in  the  way  of  securing  good  drainage.  Not  only 
as  a  commercial  speculation,  but  as  a  sanitary  measure,  the  re- 
moval of  this  sewage,  and  the  conversion  of  it,  if  possible,  into 
saltpetre,  seemed  to  be  important.  His  advice  was  not  adopted, 
and  since  that  time  his  views  had  received  confirmation  by  the 
fearful  ravages  of  disease  and  high  rate  of  mortality  which  had 
occurred  in  the  island. 
Dr.  J.  Attfield  conceived  that  the  largest  production  of  nitre 
would  not  coincide  with  the  periods  when  thunderstorms  most 
frequently  succeeded  each  other,  but  that  a  necessary  interval 
must  elapse  to  allow  time  for  the  oxidation  to  proceed. 
Dr.  Odling  referred  to  an  anomaly  in  the  fact  that  starch 
