1 8  Gleanings  from  the  German  Journals.  {Am/anl.;iSi.arm' 
tetragonal  crystals  are  obtainable,  melting  at  145-5°  C.  Isocholes- 
terin  benzoate  can  also  be  made  by  the  same  method ;  this  melts  at 
178-5°  C. — Ztschr.f.  Physiol.  Chemie,  1891,  37-48. 
A  vegetable  charcoal  is  now  being  made  by  carefully  heating  wood 
and  allied  substances  with  strongly  alkaline  solutions  under  great 
pressure ;  the  product  is  equal,  if  not  superior,  and  cheaper 
than  charcoal  obtained  from  blood.  After  use  it  can  easily  be 
regenerated  by  treatment  with  hydrochloric  acid,  ignition  and 
thorough  washing  water.  It  has  been  very  satisfactory  in  purifying 
and  clarifying  water,  organic  and  pharmaceutical  preparations,  oils, 
honey,  glycerin,  ammonia,  tannin,  vaselin,  alcohol,  etc.  In  the 
examination  of  urine  for  sugar  this  vegetable  charcoal  will  replace 
treatment  with  lead  subacetate.  Alkaline  solutions  containing  more 
alkali  than  corresponds  to  0-04  per  cent,  calcium  oxide  cannot  be 
treated  with  this  charcoal  ;  ammonia  solutions  are  exceptions  to  this. 
Odorous  and  bitter  principles  are  removed  by  using  it  in  excess, 
hence,  in  the  presence  of  these,  very  little  charcoal  must  be  used, 
generally  1  or  1-5  parts  in  1,000  is  sufficient.  Honey  has  been 
obtained  almost  colorless  by  using  larger  quantities,  but  it  was 
devoid  of  aroma ;  by  treating  the  dried  charcoal  with  ether  this  can 
again  be  extracted  and  incorporated  with  the  purified  honey. — 
W.  Miiller,  Apoth.  Ztg.,  1890,  714. 
Detection  and  estimation  of  ?iitrates  in  waters. — In  5  cc.  of  the  water 
2  centigrams  sodium  salicylate  are  dissolved,  and  10  cc.  colorless 
concentrated  sulphuric  acid  gradually  added  so  as  to  form  a  distinct 
layer ;  by  gentle  shaking,  the  two  layers  are  mixed,  a  pale  yellow 
to  deep  red  color  indicating  the  presence  of  nitrates.  This  color  is 
then  compared  with  that  obtained  by  using  dilute  potassium 
nitrate  solution  of  known  strength,  allowing  the  tests  to  become 
cold  before  comparing.  A  standard  solution  of  potassium  nitrate 
is  made  by  dissolving  1-870  gm.  pure  and  dried  salt  in  one  liter, 
this  contains  1  part  N205  in  1,000  parts;  from  this,  solutions  are 
made  containing  1  part  N205  in  5,000,10,000,  20,000,  50,000  and 
100,000  parts,  respectively.  These  solutions  are  compared  with  the 
water  to  be  examined.  The  limit  of  this  test  is  one  part  N205  in 
100,000  parts,  indicated  by  a  pale  yellow  color;  these  colors  remain 
permanent  for  several  days. — G.  Looff,  Pharm.  Centralhalle,  1890, 
700. 
