Am.  Jour.  Pharm. ) 
Aug.,  1885.  i 
Examination  of  Butter. 
401 
rapidly.  One  millionth  part  of  a  gram  of  nitric  nitrogen  can  be  de- 
tected by  this  test  when  using  1  cc.  of  liquid. 
Detection  of  Nitric  Acid  in  the  Presence  of  Nitrous  Acid. — There  is 
no  satisfactory  method  for  effecting  this  when  the  quantity  of  nitric 
acid  is  very  small,  for  nitric  acid  is  either  produced,  as  in  the  second 
and  third,  or  only  vaguely  indicated,  as  in  the  first  of  the  following 
methods.  1st.  Estimate  the  total  nitrous  and  nitric  nitrogen  as  am- 
monia or  nitric  oxide ;  and  then  the  nitrous  nitrogen  with  permanga- 
nate, or  with  phenylenediamine,  the  difference  between  the  two  estima- 
tions, is  due  to  nitric  nitrogen.  2d.  Piccini  recommends  destroying 
nitrites  by  boiling  acidified  solutions  w^ith  carbamide,  and  then  testing 
for  nitric  acid.  3d.  Muir  suggests  conversion  into  ammonium  salts, 
and  evaporating  to  dryness  to  destroy  nitrite. — Jour.  Chem.  Soc.^  May, 
1885,  p.  593;  from  Chem.  News,  [51],  39-41. 
ON  THE  EXAMINATION  OF  BUTTER. 
By  Morton  Liebschutz. 
Although  it  does  not  seem  a  matter  of  much  importance,  in  the 
abstract,  whether  the  fatty  body  used  as  food  is  derived  from  the  fatty 
deposits  of  the  animal,  or  from  the  emulsion  called  milk,  the  chemist 
is  often  compelled  to  decide  whether  a  given  sample  is  genuine  butter 
or  an  imitation. 
Dalican  has  given  a  method  based  on  the  percentage  of  insoluble  fatty 
acids.  He  asserts  that,  as  a  nearly  general  rule,  pure  butter  yields  86*5 
per  cent,  of  fatty  acids,  while  oleomargarine  shows  only  93*75  per  cent. 
His  method,  which  is  excellent  when  time  permits,  and  only  a  few 
samples  are  to  be  tested,  is  too  tedious  for  general  use.  The  washing 
of  the  fatty  acids  of  pure  butter  requires  at  least  two  days,  it  being 
considered  complete  only  when  the  water  used  for  the  operation  remains 
perfectly  neutral. 
The  determination  of  the  glycerin  would  be,  I  think,  a  shorter  way 
of  examination,  and  David^s  method  of  saponification  by  barium 
hydrate  might  be  used  with  advantage.  David  proposed  the  method 
for  the  so-called  titration  of  tallow,  his  plan  being  to  extract  the  gly- 
cerin from  a  large  sample  of  fat  (100  grams),  to  bring  the  glycerin  to 
a  known  volume,  and  to  take  its  specific  gravity.    Knowing  the  per- 
26 
