28 
Tests  for  Carbolic  Acid,  etc. 
f  A.m.  Jour.  Pharm. 
I      Jan.,  1879. 
residue  dissolved  in  90  per  cent,  alcohol,  again  evaporated,  and  so  on 
repeatedly  until  well-formed,  extremely  bitter,  colorless  crystals  are 
obtained.  The  crystals  are  completely  soluble  in  water.  These 
expriments  oppose  the  idea  that  the  "  bitter  resin  "  of  hops  can  be 
-dissolved  in  water  only  with  the  aid  of  sugar,  tannic  acid,  gum,  etherial 
oil,  etc.  The  brown  amorphous  resin  and  the  bitter  principle  of  hops 
are  two  fundamentally  different  substances. — J.  T.  four.  Chem.  Soc, 
October,  1878,  from  Dingl.  pofyt,  j£,  ccxxvii,  354 — 357. 
THE  DISTINCTIVE    TESTS    FOR    CARBOLIC  ACID, 
CRESYLIC  ACID  AND  CREASOTE. 
By  Alfred  H.  Allen. 
Several  previous  observers  have  devised  methods  of  distinguishing 
carbolic  acid  from  wood-tar  creasote,  and  have  described  tests  which 
when  applied  to  the  pure  substances  leave  little  to  be  desired. 
It  appears,  however,  not  to  have  been  observed  that  cresylic  acid, 
so  largely  present  in  the  commoner  kinds  of  carbolic  acid,  resembles 
creasote  more  closely  than  pure  carbolic  acid  does,  and  fails  altogether 
to  respond  to  some  of  the  tests  which  have  been  proposed  to  distinguish 
carbolic  acid  from  creasote.  As  the  substitution  of  coal-tar  acids  for 
wood-tar  creasote  is  pretty  certain  to  be  made  by  the  employment  of  a 
crude  variety  of  carbolic  acid,  the  presence  in  it  of  cresylic  acid  can- 
not rightly  be  ignored. 
With  a  view  to  clearing  up  the  discrepancies  between  the  results 
recorded  by  other  observers,  and  of  ascertaining  the  most  reliable  tests 
for  distinguishing  carbolic  and  cresylic  acids  from  wood-tar  creasote,  I 
have  instituted  a  series  of  special  experiments. 
As  the  origin  of  some  of  the  statements  made  by  other  observers 
cannot  be  traced,  owing  to  imperfect  descriptions  of  the  substances  on 
which  they  worked,  I  think  it  well  to  define  carefully  the  exact  sub- 
stances on  which  my  own  experiments  were  made. 
The  Carbolic  Acid  was  a  sample  of  Calvert's  No.  1,  for  internal  use  ; 
boiling  point  i82°C. 
The  Cresylic  Acid  I  prepared  by  fractional  distillation  of  Calvert's 
No.  5  carbolic  acid.  The  portion  coming  over  between  1250  and 
205°C.  was  collected  separately  and  again  distilled,  the  first  and  last 
