M2  Official  Fhlid  Acids.  {^uTc^m™' 
pharmacopoeial  description — "  a  clear,  colorless  liquid,  having  a 
strong  vinegar-like  odor,  a  purely  acid  taste,  and  a  strongly  acid 
reaction."  All  of  them,  however,  left  some  residue  upon  evapora- 
tion. None  of  the  samples  contained  copper,  lead  or  other  poison, 
ous  metals.  Samples  I,  9  and  12  were  free  from  both  hydrochloric 
and  sulphuric  acids;  samples  3,  8,  10  and  11  contained  traces  of 
sulphuric  acid ;  the  other  samples  were  contaminated  with  both  of 
these  impurities.  Only  samples  6  and  8  responded  to  the  test  for 
formic  and  sulphurous  acids.  Sample  1 1  was  the  only  one  which 
exceeded  the  limit  of  empyreumatic  substances  allowed  by  the 
Pharmacopoeia.  The  samples  contained  the  following  percentages 
of  absolute  acetic  acid  :  36-9,  44-0,  37-2,  44  9,  45-0,  31-5,  44-8,  447, 
44-8,  40-6,  50-6,  and  45-2.    The  official  strength  is  36  per  cent. 
Acidum  Hydrobromicum  Dilutum. — David  K.  Bishop,  P.D.,  titrated 
ten  samples  of  diluted  hydrobromic  acid  according  to  the  directions 
of  the  Pharmacopoeia.  By  this  means  he  found  the  strengths  of  the 
samples  to  range  as  follows:  1 0-6,  10-4,  10-9,  12-0,  io-i,  13-9,  14-3, 
15-0,  14-1,  12-3  per  cent.  The  Pharmacopoeia  requires  the  presence 
of  10  percent,  of  real  hydrobromic  acid. 
Acidum  Hydrochloricum  Dilutum. — Swain  H.  Brewton,  P.D.,  esti- 
mated the  absolute  hydrochloric  acid  contained  in  ten  samples  of 
diluted  hydrochloric  acid.  The  following  percentage  amounts  were 
found:  10-85,  n*oo,  10-09,370,  10-20,  10-30,  11-12,  8-68,  9-37  and 
11-40.  To  be  official  the  preparation  must  contain  10  per  cent,  of 
absolute  hydrochloric  acid. 
Acidum  Hydrocyanicum  Dilutum. — Claude  R.  Middleton,  P.D., 
considered  this  subject.  The  Pharmacopoeia  requires  diluted  hydro- 
cyanic acid  to  contain  2  per  cent,  of  absolute  hydrocyanic  acid. 
Pharmacists  are  directed  by  the  same  authority  to  keep  the  sub- 
stance in  small,  dark  amber-colored,  cork-stoppered  vials,  in  a  cool 
place.  But,  notwithstanding  this  direction,  the  five  different  samples 
of  the  acid  procured  were  contained  in  glass-stoppered  vials,  and 
only  one  of  these  vials  was  of  amber-colored  glass.  The  samples 
were  carefully  estimated,  using  for  each  estimation  five  times  the 
quantity  specified  by  the  Pharmacopoeia,  so  as  to  reduce  the  error 
of  titration.  The  respective  samples  showed  1-30,  1-73,  2-80,  1-69 
and  1-40  per  cent,  of  absolute  hydrocyanic  acid.  All  were  colorless 
and  all  except  Xo.  5  evaporated  conpletely  ;  it  left  a  trace  of  resi- 
due. 
