496  .    Analgetic  Action  of  Carbolic  Acid.  {Am'ocT^I£arm* 
an  hour.  This  reaction  is  very  delicate  even  in  solution  of  1:1000,000. 
The  color  disappears  at  once  when  the  mixture  is  shaken  with  zinc 
dust.  If  no  hydrochloric  acid  is  added  a  purple  precipitate  con- 
sisting of  double  arseniate  of  iron  and  gold  is  produced.  If  phos- 
phoric acid  is  used  in  place  of  arsenic  acid  a  violet  or  blue  coloration 
results. — Pharc  Centralhalle,  xxvii,  p.  321. 
THE  ANALGETIC  ACTION  OF  CARBOLIC  ACID  AND  THE 
CRESOL  GROUP  OF  COMPOUNDS. 
By  De.  R.  McNeill. 
Dr.  NcNeill  has  made  some  experiments  on  himself  and  others 
with  carbolic  acid  and  the  cresols  to  determine  whether  their  local 
anaesthetic  influence  can  be  utilized.  He  finds  that  a  mixture  of  sixty 
parts  of  acid  and  forty  of  oil  renders  the  skin  of  the  arm  insensitive 
to  pain  caused  by  superficial  incisions.  It  produces,  however,  a  sen- 
sation of  heat,  but  this  can  be  removed  without  any  interference  with 
the  anaesthesia  by  the  application  of  glycerin. 
A  mixture  of  glycerin  and  acid  will  have  the  same  effect  as  the 
oil  and  acid,  but  only  if  twenty  per  cent,  stronger.  Impure  carbolic 
acid  having  appeared  more  effective  as  a  local  anaesthetic  than  the 
absolute  phenol,  Dr.  McNeill  tried  the  effect  of  several  of  the  sub- 
stances allied  to  carbolic  acid  which  are  produced  in  the  distillation  of 
coal.  Several  of  these,  as  benzol  and  toluol,  had  no  effect.  A  mix- 
ture of  ortho-  and  para-cresol  (sold  as  cresolene)  was  found  to  have 
a  similar  effect  to  carbolic  acid,  but  was  not  so  powerful.  Paracresol,  on 
the  other  hand,  acted  more  powerfully,  equal  parts  of  this  substance 
and  oil  producing  anaesthesia. 
It  is  worthy  of  note  that  whilst  analgesia  is  produced  the  sensa- 
tion of  touch  remains,  and  that  the  deeper  parts  may  be  opened  pain- 
lessly by  introducing  some  of  the  anaesthetic  compound  into  the  tissue 
laid  open. 
Dr.  McNeill  records  some  cases  in  which  he  performed  minor  opera- 
tions without  pain  by  the  aid  of  carbolic  acid  or  cresol.  No  sloughing 
or  other  trouble  followed  their  use. 
As  a  mixture  of  glycerin  and  carbolic  acid  is  a  less  powerful  corro- 
sive than  a  mixture  of  oil  and  acicl,  Dr.  McNeill  suggests  that  glyce- 
rin should  be  administered  in  poisoning  by  carbolic  acid  instead  of 
oil. — Med.  Chronicle,  July,  1886 ;  Edinb.  Med.  Jour.,  June. 
