3 1 4  Gleanings  from  the  Foreign  Journals.  { Amju£e^7h7?rm' 
Testing  of  Salicylic  Acid. — H.  Kolbe  recommends  to  dissolve 
a  little  of  the  acid  in  10  times  its  weight  of  strong  alcohol,  and  to  allow 
the  solution  to  evaporate  spontaneously  from  a  watch  crystal.  The 
remaining  salicylic  acid  will  form  a  crystalline  ring,  which  is  perfectlv 
white  if  the  acid  was  strictly  pure,  but  will  be  of  a  yellowish  or  yellow 
color  if  it  was  precipitated  merely  without  further  purification.  If  the 
residue  has  a  brown  color  it  should  be  rejected  for  medicinal  purposes 
purposes,  even  if  the  powder  was  white. — Pha^.  Centralh.,  1876,  No.  49. 
Hager  states  that  pure  salicylic  acid,  equal  in  volume  to  the  size  of 
a  bean,  will  yield  after  agitation  with  about  5  cc.  of  pure  sulphuric  acid 
a  colorless  solution,  while  others  which  yielded  a  white  residue  from 
the  alcoholic  solution  rendered  yellowish  to  brown-yellow  solutions. — 
Ibid.,  No.  51. 
Test  for  the  Presence  of  Carbolic  in  Salicylic  Acid.— Prof. 
Alm£n  employs  for  this  purpose  ammonia  and  chlorinated  soda,  which 
produce  with  carbolic  acid  a  blue  color,  turning  red  by  acids  and  blue 
again  on  the  addition  of  an  alkali.  Solutions  of  phenol,  containing  one 
in  5,000,  produce  the  color  at  once  ;  solutions  one  in  50,000,  only  after 
24  hours.  Salicylic  acid  does  not  give  this  reaction.  It  is  important 
that  an  excess  of  chlorine  be  avoided,  and  that  sufficient  ammonia  be 
added  to  impart  an  alkaline  reaction. — Phar.  Zeitung. 
Dispensing  of  Salicylic  Acid. — In  case  salicylic  acid  be  prescribed 
with  water  in  insufficient  quantity  to  yield  a  permanent  solution,  James 
W.  White  recommends  to  dispense  it  suspended  by  the  aid  of  traga- 
canth,  20  grains  of  which  will  be  sufficient  for  a  6  oz.  mixture.  A  good 
pill  mass  will  be  obtained  by  beating  salicylic  acid  with  one-tenth  its 
weight  of  borax  and  the  same  quantity  of  glycerin  ;  6  grains  of  the 
mass  represent  5  grains  of  acid,  and  do  not  form  an  inconveniently  large 
pill. — Phar.  Journ.  and  Trans.,  Dec.  16,  1876. 
Hydriodic  Acid. — Prof.  H.  Kolbe  finds  the  following  the  most 
satisfactory  method  for  preparing  this  acid  :  A  retort  containing  10 
parts  of  iodine  is  filled  with  carbonic  acid  gas  \  afterwards  1  part  of 
phosphorus  is  introduced  in  small  quantities,  heat  is  then  applied  for  a 
short  time  to  the  liquid  mixture  of  bi-  and  teriodide  of  phosphorus,  and 
when  cooled  again  4  parts  of  water  are  added.  A  copious  evolution  of 
hydriodic  acid  gas,  free  from  iodine,  takes  place  on  the  application  of 
a  moderate  heat. — Jour.  f.  prakt.  Chem.,  1877,  p.  172. 
