676 
Lard  Adulteration  with  Cotton-Seed  Oil. 
Am.  Jour.  Pharm, 
Nov.,  1888. 
nearly  as  possible  from  the  watery  layer  which  is  syphoned  off,  and 
the  flask  filled  up  with  boiling  distilled  water  so  as  to  bring  the  acids 
into  the  neck. 
5  CO.  of  the  fused,  fatty  acids  are  now  transferred  into  a  clean,  dry, 
wide  test  tube  by  means  of  a  dry,  warm,  fast-running  pipette,  20  cc. 
absolute  alcohol  added  by  pouring  through  the  pipette  so  as  to  wash 
it,  the  solution  heated  to  incipient  ebullition  in  a  vessel  of  boiling 
water,  and  2  cc.  of  a  30  per  cent,  solution  of  silver  nitrate  added, 
when  if  even  2  per  cent,  of  cotton-seed  oil  be  present  in  the  sample, 
the  characteristic  cedar-brown  color  is  at  once  developed.  To  quan- 
tify this  reaction,  known  mixtures  of  pure  lard  and  refined  cotton- 
seed oil  are  treated  as  above,  and  the  colors  in  the  different  tubes  com- 
pared by  reflected  light  against  a  white  back-ground.  This  must  be 
done  simultaneously,  for  in  about  seven  minutes  the  coloring  matter 
begins  to  fall  out,  and  correct  comparison  is  then  impossible. 
In  this  test  a  blank  experiment  should  be  made  as  ^^pure^^  alcohol 
often  reduces  silver  nitrate  to  a  certain  extent. 
The  following  table  shows  some  of  the  results  obtained : 
Melting  point;  °C. 
Solidifying  point; 
°C  
Plummet  gravity 
at  990c  
Iodine  absorption 
per  cent  
Melting  point;  °C. 
Solidifying  point; 
°C  
Plummet  gravity 
at  99  °C  
Mean  combining 
!  weight  
j  Iodine-absorption 
per  cent  
Oleic  acid,  etc., per 
cent  
Oleic  acid,  Iodine- 
absorption  
Millian's  nitrate 
of  silver  test  
a- 
39 
26-5  rising 
to  27  5 
•8602 
55-4 
38-7  rising 
to  39  0 
•8372 
274  5 
58^3 
58-4 
87^4 
White, 
•8620 
30-5 
59-5 
?-5  rising 
to  38-8 
•8385 
White. 
•8608 
62 
Grey. 
1 8  « 
I'd .S  go 
^  o 
37^5 
27-5 
•8648 
82-5 
Marked 
black'ng. 
5  fl 
40 
30-5 
•8637 
68-8 
39-5 
'375  rising 
to  38-5 
•8450 
276-8 
70-4 
57-8 
(94.6) 
Marked 
blackening 
CO 
•8628 
62-8 
64-8 
Sensible 
darkening 
The  following  figures  are  the  recorded  results  of  experience  with  1 
tallow,  2  lard,  3  and  4  cotton-seed  oil,  5  fatty  acids  from  4  and  6  cot- 
ton-seed fat,  a  commercial  product  which  is  the  stearin  of  cotton-seed 
