266     PRODUCTION  OF  NITRATE  OF  SODA  AT  IQUIQUE  (PERU). 
and  the  whole  system  of  labor  arranged  to  it.  It  is  almost  im- 
possible to  conceive  a  system  more  rude  and  more  wasteful ;  and 
although  many  exertions  have  been  made  during  the  past  ten 
years,  without  success,  to  improve  it,  yet  that  want  of  success 
has  been  caused  chiefly  by  the  lack  of  skilled  labor  in  the  pro- 
vince ;  still  there  is  no  doubt  that  it  will  be  superseded,  in  the 
course  of  a  few  years,  by  the  more  refined  and  complicated  ap- 
paratus now  being  introduced.  The  theory  of  the  process  of 
refining  nitrate  is  this  : — "  Caleche"  consists  of  nitrate  of  soda, 
chloride  of  sodium  (common  salt),  and  earthy  matter,  (the  other 
substances  present  exist  in  such  small  quantities  that  they  are 
overlooked)  ;  and  as  chloride  of  sodium  is  very  little  more  soluble 
in  boiling  than  in  cold  water,  whilst  nitrate  of  soda  is  compara- 
tively insoluble  in  cold,  but  very  soluble  in  hot  water,  it  is  very 
evident  that  it  is  only  required  to  add  such  quantities  of 
"  caleche"  to  boiling  water  to  procure  a  strongly  saturated  solu- 
tion ;  the  earthy  matter,  being  insoluble,  is  left  with  the  excess 
of  common  salt  in  the  boiler,  or  the  deposit,  before  it  is  discharged 
into  the  coolers,  where,  as  the  liquid  cools,  it  deposits  the  excess 
of  nitrate  of  soda,  the  mother  liquor  retaining  all  the  salts  in 
solution.  Reverting  to  the  customary  process  of  refining,  two 
systems  are  now  being  tried,  which  use  steam  :  in  the  one  (Gam- 
boni's  patent)  the  "caleche"  is  placed  in  an  inverted  semi-cone, 
with  a  perforated  cover  and  bottom  ;  through  the  side  a  jet  of 
steam  is  introduced,  mother  water  is  thrown  on  the  cover,  and 
the  refined  nitrate  falls  through  the  bottom,  and  is  at  once  con- 
veyed to  the  coolers;  in  the  other,  steam  is  introduced  to  boil 
the  solution  ;  but  both  promise  the  same  advantages — economy 
in  the  make,  and  a  superior  article. 
No  sketch  of  the  nitrate  trade  would  be  complete  without 
some  reference  to  the  abuses.  In  the  first  place,  it  is  badly 
based.  The  merchant  makes  advances  to  the  soliteros,  oflS- 
cineros  (makers),  of  money  and  goods,  on  the  promise  of  receiv- 
ing in  return  the  product  of  the  oflScina.  This  advance  fre- 
quently is  used  in  paying  off  old  debts,  or  in  advances  to  the 
laborers.  The  merchant  must  still  keep  advancing  barley  for 
the  troops,  coals  and  provisions  for  the  laborer,  &c,  or  there 
will  be  no  nitrate  forthcoming.  This  system  trenches  heavily 
upon  the  merchant's  resources,  and  occasionally  leads  to  losses. 
