46 
GLEANINGS  FROM  THE  GERMAN  JOURNALS. 
bromine  in  a  sufficient  quantity  of  diluted  caustic  potassa;  most 
of  the  iron  is  then  precipitated  with  caustic  potassa,  and  the  pre- 
cipitation of  the  heated  liquid  is  completed  by  the  careful  ad- 
dition of  a  solution  of  carbonate  of  potassa.  After  standing 
several  hours,  the  precipitate  is  filtered,  washed  with  distilled 
water,  evaporated  and  allowed  to  crystallize  as  long  as  pure 
crystals  are  formed,  which  are  to  be  quickly  washed  with  a  little 
cold  water  and  dried. 
For  iodide  of  potassium,  the  formula  is  like  the  preceding,  ex 
cept  that  for  2  oz.  iron,  36  oz.  water  and  6  oz.  iodine,  and  for 
the  second  solution  2  oz.  iodine  are  employed.  The  author  pro- 
poses, after  Liebig's  suggestion  to  dissolve,  instead  of  one-third, 
one-fourth  of  the  whole  iodine  or  bromine  employed,  in  the  caus- 
tic potassa,  in  order  to  precipitate,  not  hydrated  sesquioxide,  but 
the  magnetic  oxide  of  iron,  which  is  less  voluminous,  and  there- 
fore more  easily  washed. 
On  the  decolorization  of  a  solution  of  Indigo  in  sulphuric  acid 
by  volatile  oils. — C.  Frederking,  of  Riga,  gives  the  following 
information  in  a  letter  to  Dr.  Bley,  published  in  Archiv  d. 
Pharm.  1859,  Sept.  289,  290.  The  solution  of  indigo  was  de- 
colorized by  oleum  aurantii,  anethi,  angelicae,  cassiae,  limonis, 
menth.  pip.  Amer.,  menthse  crispse,  lavandulae,  juniperi  baccse 
(commercial),  sabinse,  salvia,  saturejse  Portug,  terebinth.  It 
was  not  decolorized  by  oleum  anisi,  caryophylli,  carvi  (self-pre- 
pared), bergamottse,  cerse,  calami,  cajeputi,  foeniculi,  hyssopi, 
menth.  pip.  Germ.,  origani,  junip.  bacc.  (self-prepared),  petrose- 
lini,  serpylli,  rosmarini,  petrae,  thymi,  valerianse.  One-tenth  oil  of 
turpentine  added  to  oil  of  valerian  and  oil  of  juniper  of  his  own 
preparation,  decolorized  the  solution  of  indigo.  It  appears  that 
some  oils  may  be  tested  for  turpentine  in  the  manner  indicated.* 
On  rectifying  12  lbs,  chloroform,  C.  Frederking  obtained,  to- 
*  M.  Frederking  does  not  appear  to  have  met  with  the  observations  of 
Dr.  J.  T.  Plummer  et  On  the  discolorizing  properties  of  the  essential  oils," 
Amer.  Jour.  Phar,,  1853,  page  398 ;  and  also  at  page  408  of  the  same  vol- 
ume, in  a  paper  entitled  "Experiments  with  sulph-indig otic  acid  and  ozonous 
atmospheres."  The  reader  will  find  this  subject  interestingly  treated  of  in 
these  papers  six  years  before  M.  Frederking  was  attracted  to  the  subject. — 
Ed.  Am.  Jour.  Phar. 
