594  Decomposition  of  Quinine  Bisulphate.  {A^'eJe^rF^gf^' 
been  arrived  at :  ( I )  The  exsiccation  of  quinine  bisulphate  at  a  safe 
temperature  (e.  g.,  35°-40°  C),  before  submitting  to  higher  tem- 
peratures, raises  the  limit  of  temperature  at  which  decomposition 
is  first  noticed.  Whereas  quinine  bisulphate  C20H24N2O2,  H2S04, 
7H20  decomposed  to  the  extent  of  0.25  per  cent,  at  6o°  C,  the 
exsiccated  salt  showed  no  decomposition  at  this  temperature.  (2) 
The  addition  of  a  small  quantity  of  water  (e.  g.,  half  its  own  weight) 
at  any  dangerous  temperature  increases  the  amount  of  decomposi- 
tion, whilst  a  larger  quantity  of  water  under  similar  conditions 
retards  decomposition.  The  period  of  heating  was  twenty-four 
hours  in  all  cases. 
Table  A  at  6o°  C. 
Per  cent,  of  quinine  con- 
verted into  quinicine. 
Weight  of  bisulphate.  Weight  of  Water.  Percent. 
10  grams    nil  0.25 
10      "    5  grams.  4 
10      "   10     "  0.1 
10      "   20     "  nil 
Table  B  at  900  C. 
10  grams    nil  50 
10  "   
10  "   
10      "     20     "  18^ 
10      "    30     "  15H 
10      "    40     "  13 
10    "    50    "  ioy2 
10    "    100    "  5 
(3)  The  dangerous  limit  of  temperature  at  which  quinine  bisulphate 
heated  alone,  or  in  very  strong  solution  for  twenty-four  hours,  first 
shows  decomposition  was  found  to  be  6o°  C.  Above  this  point  de- 
composition increased,  and  at  900  C.  it  amounted  to  50  per  cent,  in 
twenty-four  hours  and  75  per  cent,  in  forty-eight  hours.  If  the 
water  of  crystallization  is  allowed  to  escape  (i.  e.,  if  the  treatment  is 
not  carried  out  in  a  closed  vessel),  the  amount  of  decomposition 
was  reduced  to  17  per  cent,  in  twenty-four  hours,  owing  to  the 
exsiccation  of  the  salt  and  consequent  raising  of  the  dangerous  limit 
of  temperature.  (4)  It  is  very  doubtful  if  melting  of  the  hydrated 
salt  can  ever  occur  without  decomposition.  (5)  In  all  cases  where 
decomposition  occurred,  a  bright  yellow  coloration  of  the  "  melt," 
giving  a  highly  colored,  very  refractory  solution  was  noticed,  and 
this  may  be  considered  a  certain  indication  of  decomposition. 
5  grams.  35 
10     "  1^/2 
