Am.  Jour.  Pharm. 
Nov.,  1886. 
Salol. 
553 
sparingly,  if  at  all  soluble  in  water  at  60°  F.  It  dissolves  in  proof 
spirit,  more  readily  in  stronger  spirit,  and  is  precipitated  on  dilution,  a 
permanent  emulsion  being  formed.  The  solution  has  no  effect  what- 
ever on  litmus. 
Salol  melts  at  106°  to  108°  F.,  forming  at  a  slightly  higher  tem- 
perature a  clear  white  liquid  like  carbolic  acid.  If  it  be  melted  under 
water  and  shaken  till  cool,  the  original  condition  of  a  coarse  crystal- 
line powder  is  restored. 
It  dissolves  readily  in  caustic  soda  solution,  and  on  addition  of  acid 
in  excess  the  liquid  becomes  milky,  oily  looking  drops  are  visible,  and 
the  smell  of  carbolic  acid  is  noticeable.  When  the  liquid  is  only 
slightly  acid,  the  addition  of  a  nearly  neutral  solution  of  ferric  chlo- 
ride produces  the  purple  coloration  indicative  of  salicylic  acid. 
The  advantages  which  are  claimed  for  salol  over  salicylate  of  soda, 
for  which  it  is  proposed  as  a  substitute,  are  dependent  first  of  all  on 
its  insolubility  in  water  and  the  juices  of  the  stomach,  and  secondly 
on  the  ease  and  completeness  with  which  it  is  decomposed  after  pass- 
ing the  pylorus.  Being  insoluble  in  water  it  is  free  from  the  repellant 
and  nauseating  effects  of  salicylate  of  soda  which  some  patients  find 
so  objectionable  that  even  syncope  has  sometimes  supervened  on  in- 
gestion. Passing  through  the  stomach  unaltered  it  undergoes  decom- 
position in  the  duodenum,  where  it  comes  into  contact  with  the  pan- 
creatic juice  and  is  broken  up  into  salicylic  acid  and  phenol.  Pro- 
fessor von  Nencki  claims  that  this  change  is  due  to  the  pancreatic 
ferment,  but  a  simple  experiment  suffices  to  show  that  so  highly  or- 
ganic a  secretion  is  not  essential  to  produce  the  effect  referred  to.  The 
pancreatic  juice  is  alkaline  in  character  and  I  find  that  the  addition 
of  a  few  drops  of  solution  of  soda  brings  about  the  decomposition, 
so  that  the  further  addition  of  ferric  chloride  is  followed  by  the  char- 
acteristic purple  coloration.  The  action  of  the  soda  takes  place  very 
slowly  in  the  cold,  more  quickly  when  gently  warmed.  The  liquid 
must  be  neutral  or  slightly  acid  for  the  color  to  be  produced,  though 
much  acid  discharges  it.  The  best  effect  is  obtained  by  digesting  salol 
in  solution  of  soda  at  100°  F.  for  an  hour,  pouring  off  the  clear  liquid, 
adding  slight  excess  of  hydrochloric  acid  and  diluting,  then  adding  a 
dilute  solution  of  ferric  chloride.  No  coloration  whatever  results 
when  salol  is  heated  with  an  acid  instead  of  alkali  previous  to  the 
addition  of  ferric  chloride. 
Now  the  salivary  secretion  also  is  alkaline  and  if  alkali  is  the  only 
