400  GLEANINGS  FROM  GERMAN  JOURNALS. 
produces  turbidity,  which,  however,  disappears  on  gentle  agita- 
tion. If  the  sample  contains  alcoholate,  the  liquid  remains  more 
or  less  turbid,  or  deposits  iodoform  crystals  after  a  time,  although 
this  is  partly  soluble  in  the  presence  of  chloral.  Of  some  com- 
mercial samples  examined  by  Hager,  Schering's  chloral  hydrate 
was  the  only  one  entirely  free  from  alcoholate. — Pharm.  Centr, 
IT.  1870,  No.  18. 
More  recently  Schering  calls  attention  to  some  more  distinc- 
tions between  chloral  hydrate  and  chloral  coholate  ;  when  warmed 
in  a  test  tube  in  twice  their  bulk  of  water,  the  hydrate,  as  known, 
dissolves  readily,  but  the  alcoholate  melts  without  solution,  and, 
on  cooling,  congeals  under  the  water.  Sulphuric  acid,  when 
warmed  with  chloral  hydrate,  remains  colorless,  whilst  it  turns 
brown  with  the  alcoholate.  When  warmed  in  nitric  acid  of  1'2 
spec,  gr.,  chloral  hydrate  gives  none  or  but  a  very  slight  reac- 
tion, whilst  with  the  alcoholate  a  vehement  reaction  ensues  under 
evolution  of  nitrous  oxid  gas. — Pharm.  Centr.  H.^  1870,  No.  26. 
Examination  of  Commercial  Sulphuric  and  Hydrochloric  Acids 
for  Arsenic. 
Sulphuric  Acid. — In  a  test  tube,  of  medium  size,  about  5 
grains  of  stannous  chloride  are  dissolved  in  4 — 6  c.  c.  pure 
hydrochloric  acid,  of  about  25  per  cent,  strength.  To  this  solu- 
tion 2 — 3  c.  c.  of  the  sample  of  the  sulphuric  acid  are  added, 
drop  by  drop,  and  with  frequent  gentle  agitation  ;  the  mixture 
evolves  considerable  heat.  If  a  white  precipitate  be  formed,  a 
few  drops  hydrochloric  acid  are  added  in  order  to  dissolve  it. 
When  the  sample  is  free  from  arsenic,  the  liquid  remains  clear 
for  quite  a  time;  but  if  arsenic  is  present  it  becomes  yellow,  and. 
turns  gradually  dark  brown  and  turbid,  and  after  some  hours 
grayish-brown  arsenic  deposits  in  flocks. 
Hydrochloric  Acid. — The  mode  of  examination  is  the  same, 
but  instead  of  the  pure  hydrochloric  acid  the  sample  to  be  exam- 
ined is  used,  and  instead  of  the  sulphuric  acid  the  monohydrate 
of  pure  sulphuric  acid. — Pharm.  Cent.  H.  1870. 
Suggestion  to  Preserve  Medicines  liable  to  Deterioration. — ■ 
Aqueous  tincture  of  rhubarb  is  a  popular  remedy  with  German 
