3° 
Cinchona  Febrifuge. 
fAm.  Jour.  Pharm. 
1      Jan.,  1877. 
the  vat,  by  means  of  a  bamboo  trough.    In  addition  to  the  macerating 
sheds,  there  is  a  small  brick  building,  heated  with  charcoal,  in  which 
the  precipitate  is  dried  ;  also  a  separate  shed,  in  which  the  process  of 
purification  is  conducted.    The  casks  are  worked  in  sets  of  three,  and 
are  marked  A,  B,  C.    In  each  shed  there  are  fourteen  sets,  seven  on 
each  side.    Each  cask  receives  one  maund  of  dry  bark,  which  under- 
goes four  successive  macerations,  the  liquor  being  moved  in  rotation 
through  the  three  casks.    Each  maceration  lasts  half  a  week.  The 
liquid  used  for  the  fourth  and  last  maceration  is  acidulated  water  drawn 
from  the  vat.    When  this  is  run  off,  it  is  moved  into  the  next  cask  to 
form  the  third  liquor.    When  this  is  drawn  off,  it  forms  the  second 
liquor  for  another  cask,  and  when  transferred  from  that,  it  goes  on  to 
new  bark,  from  which  it  is  drawn  off  and  precipitated.    Of  course,  in 
starting  a  new  shed  every  cask  contains  dry  bark,  consequently  the 
svstem  of  rotation  is  not  brought  into  full  operation  until  after  the  first 
fortnight,  and  it  is  only  after  the  shed  has  been  in  operation-  for  three 
and  a  half  weeks  that  the  liquor  for  precipitation  has  been  used  for 
four  macerations.    The  liquor  that  is  for  precipitation  is  run  into  the 
tubs.    The  other  liquors  are  drawn  into  wooden  buckets  and  poured 
into  the  proper  casks.    The  new  acid  is  then  drawn  from  the  vats. 
The  diluted  acid  is  made  in  the  vat  by  adding  one  gallon  of  muriatic 
acid  to  every  hundred  gallons  of  water — ten  fluidounces  to  each  cubic 
foot.    If  three  sheds  are  emyloyed,  No.  1  is  worked  on  Mondays  and 
Thursdays,  No.  2  on  Tuesdays  and  Fridays,  and  No.  3  on  Wednes- 
days and  Saturdays.    Each  set  of  three  casks  exhausts  one  maund  of 
dry  bark  per  week.    Three  sheds,  therefore,  containing  forty-two 
casks  each,  would  exhaust  forty-two  maunds  of  bark  every  week.  The 
weight  of  acid  used  in  the  exhaustion  is  six  and  a  half  per  cent,  of  the 
weight  of  dry  bark.    It  is  obtained  from  Mr.  Waldie's  chemical  works 
at  a  cost  of  three  and  a  half  annas  per  pound  in  Calcutta.    To  precipi- 
tate the  saturated  liquor,  a  solution  of  caustic  soda  is  added  in  excess. 
The  caustic  soda  is  obtained  from  England  in  five-cwt.  drums,  costing 
from  £15  to  £20  per  ton  in  London.    One  part  of  this  is  dissolved  in 
three  parts  of  water,  and  the  solution  stored  in  iron  vessels.  The 
quantity  to  be  added  to  the  bark  liquor  must  be  judged  of  by  the 
appearance  produced.    When  a  sufficient  quantity  has  been  introduced 
the  precipitate  assumes  a  somewhat  curdy  condition. 
About  six  and  a  half  pounds  of  solid  soda  are  used  for  every  hundred 
