Am'iug.?i893arm'}  Gleanings  from  the  German  Journals.  3,79 
ing  it  from  cotton  seed  oil  is  nitric  acid  of  specific  gravity  1-37,  the 
latter  oil  becoming  brown  while  sun-flower  oil  is  not  discolored. — 
Chemiker  Ztg.,  1893,  879. 
Picramnin,  a  crystallizable  principle  isolated  by  Dr.  Peckolt  from 
the  fruit  of  Picramnia  camboita,  Engl.,  by  extraction  with  petroleum 
ether  and  crystallization  from  alcohol,  has  been  further  studied  by 
Dr.  B.  Griitzner  with  the  result  that  both  physical  and  chemical 
properties  place  it  among  the  fats,  it  being  the  glyceride  of  an 
unsaturated  fatty  acid  and  having  the  formula  C3H5(C18H3102)3. — 
Chemiker  Ztg.,  1893,  879. 
Soluble  colloidal  barium  sulphate. — By  mixing  1 20  parts  of  a  40 
per  cent,  barium  acetate  solution  with  80  parts  of  a  60  per  cent, 
aluminium  sulphate  solution  slightly  acidified  with  acetic  acid,  a 
thick,  transparent,  pasty  mass  was  obtained  which  only  after  stand- 
ing for  some  time  precipitated  or  changed  into  the  usual  white 
barium  sulphate.  The  original  mixture  placed  upon  a  filter  gave  a 
perfectly  transparent  filtrate  which  by  diluting  with  water  gave  a 
white  turbidity  and  separated  barium  sulphate ;  the  residue  in  the 
filter  after  some  time  became  white.  Both  of  the  reagents  had 
been  prepared  with  heat  but  had  cooled  to  150  C.  before  they  were 
mixed.  An  explanation  of  this  result  on  the  ground  of  the  solu- 
bility of  barium  sulphate  in  solutions  of  aluminium  or  barium 
acetates  is  not  tenable  since  200  cc.  of  the  solution  would  have  to 
dissolve  about  36  grams  barium  sulphate. — George  Buchner, 
Chemiker  Ztg. ,  1893,  878. 
The  detection  of  cotton  seed  oil  in  lard  and  olive  oil  by  the  nitrate 
of  silver  test  is  not  trustworthy,  since  it  has  been  shown  that  cotton 
seed  oil  by  heating  loses  the  property  of  turning  brown  with  silver 
nitrate ;  F.  Gautter  has  found  the  following  modification  of  the 
sulphuric  acid  test  to  give  reliable  qualitative  results :  one  gram 
of  the  anhydrous  fat  or  oil  is  dissolved  in  10  cc.  petroleum-ether  and 
agitated  with  one  drop  concentrated  sulphuric  acid.  Pure  lard  will 
only  give  a  pale  straw  or  reddish  yellow  color,  separating  later  some 
heavy  reddish  yellow  globules  while  the  supernatant  liquid  is  colorless 
or  faintly  yellow ;  in  the  presence  of  cotton  seed  oil  an  immediate 
brown  coloration  is  noticeable  which  enables  the  detection  of  one 
per  cent,  of  the  oil.  Pure  olive  oil  generally  behaves  like  the  pure  lard, 
but  may  become  slightly  dark  ;  in  the  presence  of  cotton  seed  oil, 
