32 
ON  COTTON-SEED  OIL,  ETC. 
The  experiments  which  I  have  made  induce  me  to  regard 
the  nitrate  of  mercury  test  as  affording  sufficiently  clear  reac- 
tions to  enable  us  to  find  this  oil  when  mixed  with  olive  oil. 
I  have  used  Poutet's  test  as  follows : — 6  parts  of  mercury 
are  dissolved  in  7§  parts,  by  weight,  of  nitric  acid  1*36  with- 
out the  application  of  heat,  and  form  the  test  solution.  The 
tubes  for  making  these  experiments  are  merely  strong  test- 
tubes  of  7  inches  in  length,  and  holding  about  a  fluid  ounce. 
They  are  roughly  graduated  by  pouring  in  30  minims  of  wa- 
ter and  scratching  a  line  upon  the  glass ;  another  line  is  made 
at  the  point  reached  when  a  total  of  6  drachms  of  water  have 
been  poured  in.  The  lower  line  is  marked  "  test,"  the  upper 
one  "oil."  Pour  in  first  the  test  to  its  mark,  and  fill  up  with 
the  suspected  oil  to  the  other  line ;  shake  well  and  set  aside, 
shaking  again  about  an  hour  afterwards.  In  from  three  to 
twelve  hours,  according  to  the  temperature,  etc.,  a  genuine 
olive  oil  will  have  solidified  entirely,  the  product  after  the  lat- 
ter interval  being  quite  hard  when  touched  by  a  glass  rod. 
Cotton-seed  oil,  when  similarly  treated,*  will  not  solidify,  but 
remains  fluid.  A  mixture  of  24  parts  of  cotton-seed  oil, 
with  75  parts  of  olive  oil  gives  an  intermediate  condition. 
The  contents  of  the  tube  become  solid,  but  if  a  little  be  taken 
out  with  a  glass  rod,  it  is  found  to  be  soft,  pasty,  and  without 
any  friable  character.  On  the  other  hand,  when  pure  olive  oil 
is  so  treated,  the  product  is  hard,  friable,  and  not  pasty.  Com- 
parative trials  should  always  be  made,  and  caution  exercised 
in  accepting  the  apparent  conclusions.  Where  only  12 J  per 
cent,  of  cotton-seed  oil  is  present,  the  reactions  are  not  so  dis- 
tinct as  with  25  per  cent.,  but  I  consider  them  usually  suf- 
ficient to  decide  the  case. 
I  believe  that  when  the  adulteration  of  olive  oil  is  so  preva- 
lent as  at  the  present  time,  it  is  the  interest  of  the  members  of 
the  drug  trade  to  use  this  test  themselves,  and  also,  in  many 
cases,  to  inform  large  consumers  how  easily  it  is  applied. — 
Proceedings  of  British  Pharm.  Conf.  in  Pharm.  Jour,,  London, 
Oct.  1,  1865. 
