AmAPriir'i9f5arm"}   Wue  Hydrocarbon  in  Essential  Oils.  157 
but,  of  course,  this  requires  another  determination  and  further 
complicates  the  standardization  of  the  Na2S203  V.  S. 
In  view  of  the  close  duplicates  obtained  by  the  use  of  resublimed 
iodine  and  simplicity  of  employing  the  watch-glasses  and  clip  method, 
I  would  suggest  this  as  the  most  satisfactory  means  of  accurately 
standardizing  Na2S203  V.  S. 
The  sodium  thiosulphate  solution  was  made  by  taking  4  litres 
of  distilled  water,  boiling  until  all  air  and  C02  were  expelled,  placing 
in  a  large  amber-colored  bottle  and,  when  cool,  dissolving  about 
100  grammes  of  C.  P.  sodium  thiosulphate  in  the  liquid. 
The  bottle  was  set  away  in  a  dark  place  until  ready  for  use  (in 
about  six  weeks) .  When  a  syphon  tube  with  pinch  cock  was  inserted 
and  a  layer  of  neutral  liquid  petrolatum  placed  on  top  of  the  liquid, 
by  blowing  into  a  hollow  glass  tube  in  the  other  hole  of  the  rubber 
stopper  the  syphon  was  started. 
Making  up  the  solution  by  using  distilled  water  from  which  the 
air  and  C02  are  expelled,  allowing  to  stand  until  decomposition  and 
precipitation  have  taken  place,  covering  with  a  layer  of  liquid 
petrolatum  and  syphoning  off  the  quantities  of  solution  required, 
make  an  ideal  method  of  handling  not  only  this  volumetric  solution 
but  very  many  others,  it  being  our  practice  to  follow  this  method 
whenever  possible. 
Research  and  Analytical.  Department, 
Riker  Laboratories. 
ON  THE  BLUE  HYDROCARBON  OCCURRING  IN  SOME 
ESSENTIAL  OILS.1 
[Preliminary  Note.] 
By  Alfred  E.  Sherndal. 
Scattered  through  the  literature  of  the  essential  oils  are  frequent 
descriptions  of  blue  fractions  obtained  in  the  distillation  of  various 
oils,  the  most  intensely  colored  sections  distilling  between  the  tem- 
peratures, 275 0  and  3000,  or  higher.  A  few  oils,  such  as  those  of 
chamomile,  worm-wood,  and  cubebs,  are  notable  for  their  blue  or 
green  color  before  fractionation. 
1  Reprinted  from  Jour.  Amer.  Chem.  Soc,  1915,  p.  167. 
