1 66  Modification  of  Nessler  s  Tube.  {AmAp°riir;i?oh3arm- 
problem.  In  addition  to  the  crude  adulterants,  such  as  oil  of  tur- 
pentine and  carbolic  acid,  there  is  available  a  substance  that  is  actu- 
ally better  from  a  chemical  point  of  view  than  genuine  oil  of  winter, 
green.  From  the  comparative  prices  given  above  it  will  be  seen 
that  synthetic  oil  of  wintergreen,  as  well  as  oil  of  sweet  birch,  are 
much  lower  in  price  than  the  pure  oil  of  wintergreen.  In  addition 
to  this,  the  content  of  methyl  salicylate  is  in  inverse  ratio  to  the 
price.  Opinions  as  to  the  therapeutic  efficiency  of  the  different  oils 
differ  very  materially,  several  observers  asserting  that  natural  oil  of 
wintergreen  contains  an  irritant  body  that  is  objectionable,  while 
others  maintain  that  the  natural  oil  is  much  more  efficient  than  the 
artificial. 
If,  however,  as  is  fair  to  suppose,  methyl  salicylate  is  the  thera- 
peutically efficient  portion  of  oil  of  wintergreen,  and  if,  as  has  been 
generally  conceded,  it  is  quite  feasible  to  produce  an  absolute 
methyl  salicylate,  practically  chemically  pure,  would  it  not  be  reason- 
able to  give  this  the  preference,  and  allow  it  to  demonstrate  its 
merits,  instead  of  furnishing  it,  or  rather  buying  it,  at  a  very  material 
advance  under  another  name  ? 
From  a  casual  survey  of  the  essential-oil  question,  as  it  presents 
itself  at  the  present  time,  it  would  appear  to  be  advisable  to  favor 
the  adoption  of  active  principles  of  the  essential  oils,  wherever  possi- 
ble; and  in  cases  where  these  essential  or  active  principles  are 
obtainable  of  as  good  or  even  better  quality,  made  synthetically, 
there  would  appear  to  be  no  substantial  reasons  why  they  should 
not  be  given  the  preference. 
MODIFICATION  OF  NESSLER'S  TUBE. 
By  Herbert  J.  Watson,  P.D. 
The  "  Nessler  "  jar  is  one  of  the  most  useful  and  indispensable 
articles  in  the  laboratory.  Its  value  to  the  sanitarian  is  almost  equal 
to  that  of  the  mortar  and  pestle  or  graduate  to  the  pharmacist. 
The  hours  spent  with  this  simple  apparatus  are  long  and  tedious, 
especially  when  trying  to  secure  the  desired  shade  by  pouring  back 
and  forth  the  liquid  in  the  comparison  tube.  The  principal  use  of 
the  "  Nessler  "  jar  is  in  the  determination  of  free  and  albuminoid 
ammonia  and  the  estimation  of  nitrites  in  water.  The  determina- 
tion of  free  and  albuminoid  ammonia,  in  bacteriological  researches, 
is  another  extensive  field  for  its  use. 
