396 
Determination  of^  ^inia. 
(Am.  Jour.  Pharm. 
I       Aug.,  1880. 
excess  of  the  reagent  has  been  added,  the  liquor  acquires  an  intense 
yellow  color.  The  beaker  containing  the  liquid  with  the  precipitate  is 
now  covered  by  a  watch-glass  and  heated  on  a  water-bath  till  it  begins 
to  boil.  After  a  night's  standing,  the  beaker  is  weighed  to  ascertain  the 
amount  of  liquid,  which  is  requisite  in  order  to  be  able  to  apply  later 
a  necessary  correction.  For,  although  the  iodosulphate  of  quinia  is 
very  little  soluble  in  alcohol,  it  is  not  absolutely  insoluble,^  and  there- 
fore a  correction  must  be  applied  for  the  quantity  which  has  been  dis- 
solved, both  by  the  alcohol  used  for  the  solution  of  the  alkaloids  and 
the  alcohol  contained  in  the  reagent.  The  liquid  is  now  filtered  to 
collect  the  herapathite  on  a  small  filter,  where  it  is  washed  with  a 
saturated  solution  of  herapathite  in  alcohol.^  After  the  washing  has 
been  completed,  the  weight  of  the  funnel  with  the  moist  filter  is  taken 
and  the  filter  allowed  to  dry  in  the  funnel.  As  soon  as  it  is  dry  the 
weight  is  taken  again  to  ascertain  the  amount  of  solution  of  hera- 
pathite which  remained  in  the  filter,  and  which  left  the  dissolved  hera- 
pathite on  the  filter  after  the  evaporation  of  the  alcohol.  This  amount 
is  subtracted  from  the  total  amount  of  the  liquid,  and  for  the  remainder 
the  correction  is  calculated  with  reference  to  the  temperature  of  the 
laboratory  during  the  time  of  the  analysis.  The  dry  iodosulphate  of 
quinia  is  taken  from  the  filter  and  dried  on  a  water-bath  between 
two  large  watch-glasses  closing  tightly  upon  each  other,  so  that 
the  weight  of  the  substance  contained  in  the  glass  may  be  taken  with- 
out the  access  of  the  air.  When,  after  repeatedly  ascertaining  the 
weight,  it  remains  constant,  this  weight  is  noted  down  and  to  it  is  added 
the  product  of  the  calculated  correction.  The  sum  of  this  addition  is 
the  total  amount  of  iodosulphate  of  quinia  obtained  from  the  part 
soluble  in  ether  of  the  mixed  alkaloids  subjected  to  the  operation,  and 
from  this  weight  the  amount  of  crystallizable  quinia  can  be  calculated 
by  the  use  of  Jorgensen's  formula,  4C2oH24N202,3H2S04,2HI,I^. 
According  to  this  formula  i  part  of  iodosulphate  of  quinia,  dried  at 
^  Jdrgensen  found  that  at  a  temperature  of  6i°F.  i  part  of  alcohol  dissolves,  on 
an  average,  0*00125  part  of  herapathite. 
^  For  my  bark  analyses  I  always  keep  a  supply  of  this  solution,  made  by  putting 
an  excess  of  herapathite,  dried  at  2i2°F.,  into  alcohol  of  92  or  94  per  cent,  and 
shaking  from  time  to  time.  The  temperature  of  the  laboratory  in  which  the  analy- 
sis is  made  is  quite  indifferent,  provided  that  it  is  noted  and  does  not  change  during  the 
operation.  It  is  clear  that  the  amount  of  herapathite  dissolved  at  that  temperature 
in  the  alcohol  must  be  ascertained,  as  this  quantity  varies  with  the  temperature. 
