410 
ON  GLUCOSE. 
merits,  that  his  tests  for  alcohol,  in  this  case,  are  partly  entirely 
useless,  partly  very  difficult.  Lieben's  excellent  test  (iodoform) 
is  the  only  one  which,  with  the  aid  of  the  microscope,  approaches 
mine*  in  delicacy  ;  all  others  indicate  at  best  J  per  cent.,  while 
in  our  case  J  per  cent,  and  even  less  is  of  importance,  I  do 
not  doubt,  therefore,  that  Hager's  chloroform  still  contains  such 
traces  of  alcohol,  and  that  it  will  yet  decompose  in  the  course  of 
time. 
I  would  again  refer  to  my  former  paper  on  this  subject,  par- 
ticularly to  the  proof  that  the  officinal  chloroform  does  not  con- 
tain sufficient  alcohol  to  prevent  its  decomposition.  The  final 
sentence  in  Hager's  paper  (p.  319  of  this  Journal)  must,  there- 
fore, be  rejected.  As  long  as  the  officinal  chloroform  does  not 
contain  at  least  2  to  3  per  cent,  of  alcohol  it  must  be  kept  and 
dispensed  in  black  bottles,  to  guard  against  gradual  decomposi- 
tion in  the  light.  And  this  is  not  altered  in  the  least  by  pre- 
paring the  chloroform  from  chloral.  Erfm^t,  May  25,  1870. 
—Pharm.  Zeitung.,  1870,  N.  45,  p.  276.  J.  M.  M. 
ON  GLUCOSE. 
By  Pkof.  Charles  A.  Joy. 
In  the  year  1811,  KirchhofF,  a  celebrated  German  chemist, 
discovered  that  it  was  possible  to  convert  starch,  by  means  of 
sulphuric  acid,  into  sugar.  Great  expectations  were  founded 
upon  the  announcement  of  the  discovery,  as,  in  consequence  of 
Continental  wars  and  the  English  blockade,  sugar  had  become 
a  very  dear  article,  and  it  was  at  first  thought  that  an  ample 
supply  could  be  obtained  in  this  way  ;  but  everybody  was  destined 
to  be  grievously  disappointed  as  soon  as  the  subject  was  more 
thoroughly  investigated,  and  it  was  found  that  the  sugar  thus 
produced  was  of  a  different  character  from  that  to  be  obtained 
from  the  cane  and  beet.  Still,  the  discovery  of  Kirchhoff  was 
of  great  importance  and  has  led  to  many  practical  applications. 
It  was  soon  found  that  glucose  or  grape  sugar  could  be  made  in 
*  1  p.  bichromate  of  potassa  in  2000  water,  mixed  with  one-eighth  of  its 
volume  sulphuric  acid.  One  volume  of  chloroform  is  well  agitated  with 
half  a  vol.  of  this  mixture  and  set  aside  over  night ;  disappearance  of  the 
yellow  color  proves  the  presence  of  alcohol. 
