^'^'o^u'im^'''^'}    British  Pharmaceutical  Confei^ence.  537 
ii.  804).  Another  sample  that  had  been  kept  in  stock  for  a  long  time  was  pale 
brown,  and  the  specific  gravity  only  0.9194.  Guibourt  says  that  an  oil  distilled 
by  himself  from  Melaleuca  leaves  had  a  fine  green  color  ;  but  Histed  says  that 
ordinary  cajeput  oil  after  being  redistilled  is  white,  though  it  becomes  again 
green  if  placed  in  contact  with  copper  turnings.  Mr.  West  incidentally  called 
attention  to  the  fact  that  for  histological  purposes  this  oil  is  to  be  preferred  to 
oil  of  cloves  in  transferring  sections  from  alcohol  to  Canada  turpentine,  as  it 
penetrates  more  quickly  than  oil  of  cloves,  and  is  expelled  more  readily  from 
the  turpentine  afterwards. 
Cotton-Seed  Oil  in  Lard. — The  practice  of  adulterating  lard  with  cotton -seed 
oil,  which  appears  to  have  developed  recently  in  the  United  States  to  an  enor- 
mous extent,  has  rendered  very  desirable  the  publication  of  a  good  test  for 
the  detection  of  the  fraud.  In  the  next  paper  read,  on  "  Lard  :  its  Adulteration 
with  Cotton-Seed  Oil  and  Detection  thereof,"  Mr.  Conroy  gave  the  results  of  his 
experiments  in  this  direction.  The  nitric  acid  test  proposed  some  years  since 
by  Mr.  Conroy  for  the  detection  of  cotton-seed  oil  in  olive  oil  proved  not  quite 
satisfactory  when  applied  to  lard,  and  he  prefers  a  modification  of  Milliau's 
test,  dependent  upon  the  reduction  of  silver  nitrate.  This  consists  in  adding 
twenty  grain  measures  of  a  test  solution,  containing  five  parts  of  silver  nitrate 
and  one  part  of  nitric  acid  (sp.  gr.  1-42)  in  one  hundred  parts  of  rectified  spirit, 
to  about  one  hundred  grains  of  the  lard  previously  melted  at  a  water-bath 
temperature  in  a  test-tube  and  keeping  the  mixture  in  boiling  water  for  five 
minutes.  Pare  lard  remains  perfectly  white,  but  if  adulterated  with  cotton- 
seed oil  the  lard  assumes  a  more  or  less  olive-brown  color  according  to  the 
amount  of  the  adulterant  present,  1  per  cent,  causing  a  distinctly  perceptible 
change.  The  reading  of  this  paper  was  followed  by  an  animated  discussion,  in 
the  course  of  which  Mr.  W.  Thompson  expressed  an  opinion  that  whilst  free- 
dom from  blackening  might  be  accepted  as  evidence  of  the  absence  of  cotton- 
seed oil  from  a  sample  of  lard,  the  reduction  of  silver  nitrate  was  not  neces- 
sarily evidence  of  its  presence 
This  brought  the  business  of  Tuesday  to  an  end,  and  many  of  the  members 
availed  themselves  of  opportunities  afforded  them  by  the  courtesy  of  the  au- 
thorities for  visiting  the  Abbey  Church  and  the  Grand  Pump  Room  and 
Baths. 
Insect  Powder. — The  business  of  the  Conference  on  Wednesday  morning  com- 
menced with  the  reading  of  a  paper  by  Mr.  John  Kirkby,  on  Insect  Powder. 
With  a  view  to  the  detection  of  the  introduction  of  foreign  substances  into  in- 
sect powder  the  author  has  submitted  the  flower  heads  of  authentic  specimens 
of  Chrysanthemum  cincraricefolium,  the  reputed  source  of  Dalmatian  insect  pow- 
der, to  a  microscopical  examination  with  a  view  to  the  detection  of  histological 
elements' characteristic  of  the  species.  These  he  believes  he  has  found  in  the 
pollen  grains  and  the  epidermal  papillse  of  the  ligulate  florets,  of  which  draw- 
ings were  shown.  The  papillse  differ  somewhat  even  from  those  of  the  ligulate 
florets  of  C.  roseum,  the  source  of  Persian  insect  powder,  and  could  be  used  as  a 
means  of  detecting  that  admixture.  The  paper  gave  rise  to  a  lively  discussion, 
and  the  necessity  for  some  test  for  the  determination  of  the  purity  of  this  arti- 
cle was  evidenced  by  a  statement  by  Mr.  Conroy  to  the  effect  that  reputed  Dal- 
matian insect  powder  may  be  bought  at  a  much  lower  price  per  pound  than  the 
flowers  from  which  it  is  supposed  to  be  ground.   Mr.  Conroy  also  pointed  out 
