420  GLEANINGS  FROM  THE  GERMAN  JOURNALS. 
brown  deposit,  approaching  black,  in  proportion  as  the  nitro- 
benzole  is  in  excess  occurs.  This  reaction  is  instantaneous  and 
when  the  oil  contains  from  30  to  50  per  cent,  of  nitro-benzole 
one  minute  is  sufficient  to  obtain  a  thick  brown  liquid, — Jour,  de 
Pharm. 
GLEANINGS  FROM  THE  GERMAN  JOURNALS. 
Detection  of  minute  quantities  of  Mercury. — F.  C.  Schneider, 
in  an  essay  «  On  the  chemical  and  electrolytic  behaviour  of  mer- 
cury," states,  that  the  slightest  traces  of  this  metal  in  solution, 
may  be  recognised  by  immersing  in  the  liquid  to  be  examined, 
the  poles  of  a  galvanic  battery,  both  of  which  should  be  of 
gold.  Upon  the  surface  of  the  negative  pole,  a  coating  of  gold 
amalgam  is  thus  deposited,  which  is  then  to  be  removed  to  a 
test  tube.  This  tube,  after  being  hermetrically  sealed,  is 
strongly  heated,  whereupon  the  mercury  is  sublimed,  and  col- 
lects in  the  further  end  of  the  tube.  The  addition  of  a  crumb 
of  iodine  and  gentle  heat,  is  sufficient  to  produce  the  easily  re- 
cognized red  iodide  of  mercury  N.  Jahrb.  Ph.  xx.  309. 
Cotton  Seed  Oil. — Lipowitz  states,  that  the  deep  brown  com- 
mercial oil  parts  with  its  coloring  matter  readily  by  treatment 
with  alkaline  solution,  yielding  from  80  to  85  per  cent,  of  a 
clear  yellow  oil,  which  is  almost  entirely  without  smell,  and  resem- 
bles in  taste  the  finest  salad  and  poppy-seed  oils.  It  solidifies  at 
from  3°  to  0°  C.  The  crude  oil,  which  may  be  ranked  among 
the  drying  oils,  has  a  sp.  gr.  of  «928  at  15°  C.  the  purified  oil 
of  -9206.  The  fatty  portion  of  the  crude  oil  amounting  to  15 
or  20  per  cent.,  which  is  readily  saponified  by  alkalies,  may  be 
obtained  by  the  action  of  acids  upon  the  soap  in  the  form  of  a 
brownish  or  greenish  buttery-like  mass,  which  is  well  adapted  for 
a  wagon  or  machine  grease,  since  it  remains  fluid  a  long  time  in 
a  warm  place,  and  does  not  resinify.  It  may  also  be  used  for 
the  preparation  of  an  odorless  potash  or  soda  soap. — JSF.  Jahrb. 
Ph.  xx.  330. 
Indestructible  Writing  Lucas  proposes  for  this  purpose,  an 
ink  composed  of  20  grains  of  sugar  dissolved  in  30  grains  of 
