EXAMINATION  OF  THE  SULPHATE  OF  QUINIA. 
397 
Subjected  then  to  a  dry  heat  of  180°  to  212?  in  a  steam  kettle, 
for  sixteen  hours,  they  suffered  an  additional  mean  loss  of  19.04 
grains. 
Exposed  again  at  ordinary  temperatures  for  twenty-four  hours 
the  mean  weight  arose  to  391.5  grains. 
This  alternate  heating  and  exposure  was  repeated  a  second 
and  third  time  with  similar  results.  The  greatest  mean  loss 
being  19.8  grains  per  ounce,  or  an  additional  loss  upon  the 
391.18  grains  of  5.06  per  cent.  The  entire  loss  upon  the  four- 
teen ounces  heated  to  212°  was  66.12  grains  each,  or  15.11  per 
cent. 
The  salt  finally  exposed  during  a  very  rainy  night  and  morn- 
ing regained  a  mean  of  392.19  grains,  when,  after  mixing  the 
whole  fourteen  ounces  very  thoroughly  together,  the  salt  was 
restored  to  the  bottles,  putting  up  only  about  12 1  scant 
avoirdupois  ounces  of  the  salt  as  it  is  usually  dispensed  and 
administered.  The  half  bottle  was  reserved  for  the  after  experi- 
ments, and  marked  impure  sulphate,  effloresced. 
In  the  following  experiments  it  became  necessary  to  use  a  more 
delicate  balance,  and  the  French  decimal  weights.  The  avoirdu- 
pois ounce  should,  by  calculation,  be  equal  to  28.3165  grammes ; 
but,  in  practice,  with  our  balance  and  weights  it  is  equal  to 
28.4856  gram.,  and  this  latter  is  therefore  taken  as  the  basis  of 
the  calculations. 
The  authoritative  composition  of  the  officinal  disulphate  of 
quinia  is  as  follows : 
2  eqs.  Qn  =  324  =  74.31  per  cent,  =  21.1682  gramvor  325.115  grs.  per  oz. 
1  eq.    S03  =    40  =    9.17       "         =   2.6133      "      or   46.137    «  '< 
8  eqs.  HO  =    72  =  16.51       "         =   4.7040      "      or   72.247    «  " 
N  436       99.99  '     28.4855  437.499 
Experiment  No.  2. 
The  contents  of  a  new  bottle  of  the  commercial  salt  was  taken 
and  found  to  weigh  28.5050  gram.,  but  assumed  at  28.4856  gram. 
This  dissolved  very  easily  in  28.5  times  its  weight  of  boiling 
distilled  water.  This  solution  was  boiled  in  a  flask  till  .the  pro- 
portion of  water  was  reduced  to  23.96  times  the  weight  of  the 
salt,  and  the  boiling  point  arose  to  216°.  After  being  removed 
from  the  flame,  it  remained  perfectly  free  from  any  appearance 
