Am  Jour.  Pharm.  ) 
Oct.,  1877.  / 
Laboratory  Notes, 
483 
each  portion  to  represent  the  0*280  gram  as  dried  at  2I2°F.  The 
volume  of  Mayer's  solution  required  for  each,  as  given  above,  very 
nearly  coincides  with  0*280  of  Mayer's  quinia.  Farther  investigation 
is  desirable  as  to  presence  and  proportion  of  combined  water  in  the 
residue  of  quinia  at  212°F.  Mr.  A.  H.  Allen1  has  reported  the  residue 
from  ether  solution  to  retain  constant,  at  2I2°F.,  4*28  per  cent,  of 
combined  water,  a  little  less  than  that  of  a  monohydrate.  From  this 
report  Mr.  A.  N.  Palmer2  dissents,  stating  that  a  residue  of  constant 
weight  can  only  be  obtained  at  260  to  2700  F.    See  IV. 
The  precipitate  by  potassium  mercuric  iodide  is  very  close,  and  bears 
water-washing  without  weighable  loss.  The  reagent  need  not  be  of 
standard  strength  for  gravimetric  results  ;  it  can  be  prepared  simply  by 
treating  solution  of  corrosive  chloride  of  mercury  with  solution  of 
iodide  of  potassium  until  the  precipitate  at  first  formed  is  just  all  dis- 
solved. (For  the  execution  of  the  determinations  given  in  this  note  I 
am  indebted  to  Messrs.  J.  J.  Johnston  and  A.  S.  Lobb.) 
III.  Gravimetric  Determination  of  Quinia  as  a  Precipitate  by 
Phosphomolybdate . 
This  precipitate  is  exceedingly  close  in  the  case  of  quinia,  and  bears 
washing  without  loss,  but  does  not  bear  a  temperature  above  I58°F. 
(yo°C)  without  reduction  of  molybdenum,  shown  by  a  blue  color. 
The  value  of  the  precipitate,  dried  below  I58°F.  to  a  constant  weight, 
was  found  by  Mr.  Lobb  to  be  3*665  grams  for  1  gram  of  quinia  as 
dried  at  2i2°F.  This  result  was  the  mean  of  two  nearly  identical 
determinations,  0*280  gram  of  the  alkaloid  giving  respectively  1*026 
and  1*0265  gram  precipitate.  The  reagent,  the  acidulate  solution  of 
sodium  phosphomolybdate,  is  added  in  slight  excess,  when  the  precipi- 
tate separates  admirably. 
IV.  Solubility  of  Quinia  Precipitate  in  Washed  Ether. 
This  was  found  by  Mr.  Lobb  to  be  20  parts  of  the  ether  for  1  part 
of  quinia  (monohydrate),  after  24  hours  digestion  in  a  stoppered  jar. 
A  portion  of  the  saturated  ether  solution  was  drawn  into  a  specific 
gravity  bottle  and  its  weight  obtained,  then  poured,  with  the  ether  rins- 
ing, into  a  thin  glass  evaporating  dish  (tared),  the  ether  evaporated,  the 
residue  dried  at  2I2°F.   A  constant  weight  was  believed  to  be  obtained, 
1  "  Phar.  Jour  and  Trans. vi,  964,  June  3,  1876.    2  Ibid.,  vii,  89,  July  29,  1876. 
