EXAMINATION  OF  THE  SULPHATE  OF  QUINIA.  405 
the  same  subject,  and  with  the  same  results,  which  will  be  alluded 
to  hereafter. 
Dr.  Squibb's  inference,  in  his  first  communication,  is  based  prin- 
cipally upon  a  larger  loss  of  the  sulphate  in  drying  within  cer- 
tain points  of  temperature,  than  is  stated  by  some  authors,  which 
he  now  acknowledges  to  have  been  practically  and  technically 
incorrect.  His  remarks  upon  our  pecuniary  sensibilities  might 
have  been  correct,  had  no  other  issues  been  involved,  and  his  con- 
cluding remark  in  the  same  paragraph  we  cannot  think  sustained 
by  his  subsequent  experiments.  Our  experiments,  which  he  seems 
now  to  think  "  are  even  less  accurate  than  the  statements  they 
propose  to  correct,"  have  been  verified  by  repetition,  and  still 
further  extended  by  additional  ones,  and  we  see  no  reason  to 
change  the  inferences  then  made. 
We  have  assumed  the  statement  of  Soubeiran,  quoted  in 
brackets  by  Dr.  Wood,  to  be  correct,  and  Liebig  agrees  in  the 
same  calculation,  that  sulphate  of  quinia  loses  six  atoms  of  its 
water  of  crystallization  by  exposure  to  warm  dry  air ;  this  was 
the  result  of  our  experiments.  We  can  see  no  inaccuracy  in  this. 
If,  however,  we  assume  the  loss  to  be  only  four  atoms  by  ex- 
posure, as  is  stated  by  Dr.  Wood,  quoting  from  Philips,  then  Dr 
Squibb's  assertion  may  be  correct.  Of  the  eight  atoms  of  water 
of  crystallization,  most  authors  consider  two  as  being  retained  at 
any  temperature  short  of  fusion  and  decomposition.  Dr.  Squibb 
has  again  been  led  to  infer  from  this  that  there  is  still  more 
water  in  combination  with  our  sulphate  than  ought  to  be.  Our 
recent  experiments  have  led  us  to  think  differently.  Which  of 
the  two  are  right,  others  must  determine. 
In  drying  either  sulphate  of  quinia  or  the  alkaloid,  much 
depends  upon  how  it  is  subjected  to  the  action  of  heat,  whether 
exposed  with  a  large  surface  to  a  heated  dry  atmosphere,  or 
whether  enveloped  in  paper,  or  in  a  capsule  on  a  hot  surface, 
heated  by  steam  or  otherwise.  In  the  latter  case,  but  a  small 
>po'mt  of  the  capsule  comes  in  contact  with  the  heated  surface, 
rarely  heating  the  material  to  be  dried  to  the  same  temperature  ; 
and  if  it  is  thick,  rendering  a  prolonged  exposure  with  much 
stirring  necessary  to  bring  all  the  particles  in  contact  with  the 
hot  point.  May  not  some  of  the  differences  of  authors  be  owing 
to  the  different  modes  of  ascertaining  the  loss  in  drying  ? 
