128 
lodo-Sulphate  of  Chinioidin. 
J  Am.  Jour.  Pharm. 
\      Mar.  1876. 
obtained  from  a  sample  of  cinchona  bark,  1  part  of  the  alkaloids  is  dis- 
solved in  20  parts  of  alcohol  of  90  or  92  per  cent.,  containing  i'6  per 
cent.1  of  sulphuric  acid,  to  obtain  an  alcoholic  solution  of  the  acid 
sulphates  of  the  alkaloids.  From  this  solution,  the  quinia  is  separated 
by  adding  carefully,  by  means  of  a  pipette,  the  above-mentioned  solu- 
tion of  iodo-sulphate  of  chinioidin,  as  long  as  a  dark  brown  red  pre- 
cipitate of  iodo-sulphate  of  quinia  (herapathite)  is  formed.  As  soon  as 
all  the  quinia  has  been  precipitated,  and  a  slight  excess  of  the  reagent 
has  been  added,  the  liquor  acquires  an  intense  yellow  color.  The 
beaker  containing  the  liquor  with  the  precipitate,  is  now  covered  by  a 
watch  glass  and  heated  on  a  water-bath  till  the  liquid  begins  to  boil.2 
After  cooling,  the  beaker  is  weighed,  to  ascertain  the  amount  of  liquid, 
which  is  necessary  in  order  to  be  able  to  apply  later  the  above-men- 
tioned correction.  For  although  the  quinia-herapathite  is  very  little 
soluble  in  alcohol,  it  is  not  insoluble,3  and,  therefore,  a  correction  must 
be  applied  for  the  quantity  which  has  been  dissolved  both  by  the 
alcohol  used  for  the  solution  of  the  alkaloids,  and  the  alcohol  contained 
in  the  reagent.  The  liquor  is  now  filtered,  to  collect  the  iodo-sulphate 
of  quinia,  on  a  small  filter,  where  it  is  washed  with  a  saturated  solution 
of  herapathite  in  alcohol.4  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  herapathite  which  remained 
in  the  filter,  and  which  left  the  dissolved  herapathite  on  the  filter  after 
1  This  quantity  is  quite  sufficient  to  transform  the  alkaloids  into  acid  sulphates, 
and  ought  not  to  be  increased,  for  an  excess  of  acid  would  increase  the  solubility  of 
the  herapathite  in  alcohol. 
2  If  during  the  addition  of  the  reagent  to  the  solution  of  the  mixed  alkaloids,  the 
liquid  is  not  continuously  stirred,  it  may  happen  that,  if  cinchonidia  is  present  in 
large  proportion  relatively  to  quinia,  as  in  Indian  red  bark,  an  orange-colored 
gelatinous  precipitate  is  formed  of  an  iodo-sulphate  of  cinchonidia  If  this  happens, 
the  liquid  must  be  heated  till  this  gelatinous  precipitate  disappears,  before  adding 
more  of  the  reagent  to  precipitate  all  the  quinia. 
3  Alcohol  of  92  per  cent.,  saturated  with  herapathite  at  a  temperature  of  24*5°  C. 
left  by  evaporation  0*133  gram  of  herapathite. 
4  For  my  bark  analysis,  I  always  keep  a  supply  of  this  solution,  made  by  putting 
an  excess  of  herapathite  dried  at  ioo°  C.  into  alcohol  of  92  per  cent.,  and  shaking 
from  time  to  time.  The  temperature  of  the  laboratory  in  which  the  analysis  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. 
