526 
HYDRATE  OF  BROMAL. 
ESTIMATION  OF  GLUCOSE  IN  COMMERCIAL  SUGARS. 
By  J.  MiDY. 
The  author  prepares  a  Fehling  test-liquor  of  such  a  strength 
that  100  c.c.  thereof  are  completely  decomposed  by  1*05  grms. 
of  uncrystallizable  sugar  (1  c.c.  of  the  liquor  agrees,  therefore, 
with  0*0105  of  glucose) ;  a  solution  is  also  made  of  20  grms.  of 
the  sugar  to  be  tested  in  150  c.c.  of  distilled  water.  To  this 
solution,  previously  heated  till  near  its  boiling-point,  is  added, 
by  means  of  a  Mohr's  burette  (divided  into  I'lOth  c.c),  -J  c.c. 
of  the  Fehling  cupreous  liquor  ;  the  sugar  solution  is  withdrawn 
from  the  source  of  heat,  and,  after  having  been  stirred  up,  the 
suboxide  of  copper,  if  any  has  been  formed,  is  allowed  to  settle. 
When  this  has  taken  place,  a  very  small  portion  of  the  liquid  is 
filtered  through  Swedish  filtering  paper,  and  to  the  filtrate  is 
added  a  drop  of  a  concentrated  solution  of  ferrocyanide  of  potas- 
sium and  acetic  acid.  If  too  much  of  the  cupreous  test-liquor 
has  been  added,  the  addition  of  the  reagents  alluded  to  will  have 
the  effect  of  causing  the  formation  of  the  well-known  precipitate 
of  ferrocyanide  of  copper  ;  and,  in  that  case,  a  fresh  sugar  solu- 
tion has  to  be  made,  and  only  ^  c.c.  of  the  cupreous  test-liquor 
has  to  be  added  ;  and  the  ferrocyanide  should  not  give  indica- 
tions of  excess  of  copper  in  the  filtered  liquid  as  above  alluded 
to.  Such  being  the  case,  the  operator  knows  that  20  grms.  of 
sugar  contain  less  than  0*0052,  and  more  than  0*0026,  of  glu- 
cose ;  taking  the  average  of  these  figures,  which  is  0*0039,  and 
multiplying  by  5,  we  learn  that  the  sample  of  sugar  tested  con- 
tains about  0*0195  per  cent,  of  glucose. — Loud.  Qhem.  News 
Sept.  2,  1870,  fro7n  Revue  Hehdomadaire  de  CMmie,  July  28, 
1870. 
HYDRATE  OF  BROMAL. 
There  is  a  valuable  article  by  Dr.  E.  Steinauer,  of  Berlin,  in 
the  last  volume  of  "  Yirchow's  Archiv,''  on  the  action  of  the  hy- 
drate of  bromal  on  animals  and  on  man.  The  experiments  were 
made  in  the  Berlin  Pathological  Institute,  and  were  under  the 
immediate  observation  of  Liebreich  himself.     The  hydrate  of 
