Am.  Jour.  Pharm. " 
Nov.,  1888. 
Lard  Adulteration  with  Cotton-Seed  Oil. 
'77 
oil,  the  ordinary  cotton-seed  stearin  of  commerce  is  the  stearic  acid 
from  cotton-seed  oil. 
Melting  point ;  °C. 
I  Solidifying  point ;  °C. 
es  J  Plummet  gravity  at  99°C. 
lo  dineabsorption,  per  cent 
Saponification  equivalent ... 
Acidity  (=  oleic  acid)  
Melting  point ;  °C  
j  Solidifying  point;  °C  
>>  j  Plummet  gravity  at99°C  
■Jl  I  Iodine  absorption,  per  cent . 
1 
Tallow. 
40 
41- 
2 
Lard. 
•860 
'861 
Cotton - 
62 
38 
■64-2 
I  -872 
105 
110 
 ■} 
30 
•8467 
115^7 
oil 
•8725 
108 
110 
285 
294 
trace 
5 
Fatty 
acids 
from  4. 
35 
32 
.8476 
115-8 
289 
97-6 
Cotton- 
seed fat. 
40 
31  rising 
to  32-5 
89-1 
•84 
Lard  differs  materially  in  its  iodine-absorption  from  beef-stearin  on 
the  one  side  and  cotton-seed  oil  on  the  other.  There  is  also  a  marked 
difference  in  the  specific  gravity  of  lard  and  cotton-seed  oil,  and  this 
difference  is  also  noticeable  in  the  fatty  acids.  On  the  other  hand, 
lard  and  beef-fat  are  substantially  of  the  same  density.  This  differ- 
ence is  very  important,  as  it  would  enable  one  to  distinguish  a  mix- 
ture of  beef-stearin  and  cotton-seed  oil  having  an  iodine-absorption  of 
about  60,  from  genuine  lard.  Thus,  while  the  proportion  of  the  adul- 
terant in  a  mixture  composed  of  lard  and  cotton-seed  oil  only  can  be 
ascertained  with  considerable  accuracy  by  determining  the  iodine-ab- 
sorption, the  estimation  will  be  below  the  truth  if  beef-stearin  be 
present.  On  the  other  hand,  the  presence  of  beef-stearin  does  not  in- 
terfere with  the  deduction  to  be  drawn  from  the  increased  specific 
gravity  of  the  melted  sample.  Hence  this  method,  though  not  afford- 
ing more  than  approximate  results,  is  calculated  to  do  very  good 
service  in  conjunction  with  the  iodine-absorption. 
Analysts  are  cautioned  by  J.  Campbell  Brown  against  two  errors 
they  are  liable  to  make  in  trusting  the  iodine-absorptions  published. 
1.  Liability  to  underestimate  the  proportion  of  cotton-seed  oil  and 
other  foreign  fats  in  adulterated  lard.  The  substance  used  by  about 
twenty-five  American  firms  is  a  mixture  of  cotton-seed  oil  and  beef- 
stearin,  the  residue  from  the  manufacture  of  oleo-margarine.  The 
iodine-absorption  of  any  mixture  that  can  be  used  for  mixing  in  large 
proportions  with  lard  is  much  lower  than  that  of  cotton-seed  oil — not 
