406  The  Cohesion-Figures  of  Oils,  etc.      { ^gft 
ing  the  base  to  be  alumina.  To  the  remaining  portion  of  the  soda 
solution,  after  super-saturation  with  nitric  acid,  solution  of  molybdate 
of  ammonium  was  added,  no  reaction  took  place,  even  after  long 
standing,  showing  the  entire  absence  of  phosphoric  acid. 
Prof.  J.  M.  Maisch  has  noticed  the  presence  of  earthy  phosphates 
in  nux  vomica  \_Amer.  Journ.  Pharm.,  Vol.  32,  p.  524].  In  this  in- 
stance the  phosphoric  acid  may  have  been  removed  by  long  digestion 
with  dilute  sulphuric  acid  and  subsequent  precipitation  by  soda. 
The  presence  of  alkaloids  in  the  oil  rendered  apparent  the  sugges- 
tion of  Prof.  Procter,  that,  when  the  oil  is  removed,  it  should  be 
agitated  with  a  little  dilute  alcohol,  which  takes  from  it  any  adhering 
extractive  matter.  Vide,  note  to  ext.  nux  vomica,  U.  S.  Dispensatory. 
Philadelphia,  August,  1874. 
THE  COHESION  FIGURES  OF  OILS  AS  TESTS  FOR  THEIR 
IDENTITY  AND  PURITY. 
By  Miss  Kate  Crane. 
Becoming  interested,  from  articles  in  the  Chemical  News  of  1869, 
in  the  cohesion-figures  of  oils  as  tests  for  their  identity  and  purity,  I 
was  led  a  few  weeks  ago  to  experiment  with  some  varieties,  and  upon 
the  suggestion  of  a  friend  I  submit  an  account  of  some  of  my  work 
to  the  readers  of  the  American  Journal  of  Pharmacy. 
With  the  comparatively  few  trials  I  have  made  I  am  convinced 
that  a  little  patient  practice  will  teach  the  eye  in  a  short  time  to  de- 
tect the  characteristic  differences  of  the  figures.  To  make  these  per- 
fect it  is  necessary  to  observe  the  time  in  forming,  for  at  different 
periods  some  varieties  form  figures  very  like,  but  with  this  precaution 
each  is  entirely  characteristic.  It  is  essential  that  the  dish  used,  &c, 
be  perfectly  clean,  so  that  when  filled  with  water  no  dust  or  lint  floats 
upon  the  surface,  as  this  materially  interferes  with  the  perfect  forma- 
tion of  the  figure. 
A  single  drop  is  let  fall  from  a  burette  or  glass  rod,  held  steadily 
about  four  inches  above  the  water,  upon  the  centre  of  the  surface. 
I  experimented  with  a  number  of  volatile  oils,  by  themselves  and 
mixed  in  different  proportions  with  oil  of  turpentine. 
The  last-named  oil,  by  itself,  spreads  instantly  to  the  whole  size  of  the 
plate,  a  common  soup  plate,  and  almost  immediately  the  edge  begins 
to  break  into  irregular  shapes,  when  a  rapid  motion  takes  place  over 
