574  Lard  Adulteration  with  Cotton-Seed  Oil  {^^iJo^^.^'ilS^^^- 
of  cholesterin,  and  that  vegetable  fats  contain  phytosterin.  Fifty  gm. 
of  fat  is  saponified  with  alcoholic  potash,  the  soap  well  shaken  out 
with  ether,  the  ether  distilled  off,  the  residue  once  more  treated  with 
alcoholic  potash  and  ether,  and  the  residue  dissolved  on  a  watch-glass 
in  a  few  drops  of  hot  alcohol.  The  long  needles  of  phytosterin  ob- 
tained in  the  presence  of  a  vegetable  fat  melt  at  132°C.,  and  treated 
with  chloroform  and  sulphuric  acid  form  a  bluish  solution.  Choles- 
terin  crystallizes  in  flat  tablets,  melts  at  146°,  and  with  the  above  test 
gives  a  red  solution.  The  difference  of  cblor  is  strongly  marked  if 
the  solution  is  allowed  to  stand  in  a  corked  test  tube  for  several 
days. 
6.  Maumene^s  test. — Used  as  a  quantitative  test  but  to  succeed  the 
lard  must  first  be  entirely  deprived  of  moisture  by  heating  over  a 
Bunsen  burner.  50  gm.  of  pure  lard  with  10  cc.  strong  sulphuric  acid, 
show  arise  of  from  24  to  27*5°C.;  cotton-seed  oil  of  about  70°C.  In 
every  case  a  lard  which  reduces  silver  shows  a  rise  higher  than  27*5°, 
the  increase  being  proportional  to  quantity  of  cotton-seed  oil. 
7.  Iodine-absorption. — A  reliable  test  in  the  absence  of  stearin, 
which  is  added  to  lard  heavily  adulterated  with  cotton-seed  oil,  to 
counteract  the  softening  effect  of  the  latter.  Stearin  absorbs  much 
less  iodine  than  cotton-seed  oil,  therefore  the  addition  of  a  large  per- 
centage of  stearin  reduces  the  iodine  absorption  of  the  mixture  to  a 
greater  or  less  extent ;  it  is  rarely,  however,  that  the  stearin  is  present 
in  such  quantity  as  to  absolutely  nullify  the  test.  American  lard  ab- 
sorbs from  60-62  per  cent,  iodine ;  English  lard  appears  to  absorb 
less — from  51*5  to  62  per  cent.;  beef  stearin,  21  per  cent.;  lard  oil, 
fresh,  73-74  per  cent.;  old  lard  oil,  believed  to  be  pure,  41  per  cent.; 
cotton-seed  oil,  105-110  per  cent.  Some  lards  examined  absorbed  as 
much  as  85  per  cent.,  while  numerous  samples  required  70-75  per 
cent.,  leaving  no  doubt  of  their  adulteration  with  cotton -seed  oil. 
Weigh  about  0*5  gm.  of  the  melted  lard  into  a  three-ounce  wide- 
mouthed  stoppered  bottle,  melt  the  fat  by  placing  the  bottle  on  a  wa- 
ter-oven, and  when  nearly  cool  dissolve  the  fat  by  adding  10  cc.  chloro- 
form, 20  cc.  HiibPs  reagent  (5  gm.  I  and  6  gm.  HgClg  are  each  dis- 
solved in  100  cc.  96  per  cent,  alcohol,  the  solutions  mixed  and  al- 
lowed to  stand  over  night  before  use)  are  carefully  measured  into  the 
bottle  after  it  has  become  quite  cold,  and  set  aside  for  three  hours ;  at 
the  end  of  this  time  the  color  must  be  decidedly  brown,  showing  ex- 
cess of  iodine,  or  else  the  operation  must  be  repeated,  using  less  fat. 
