300  The  Pharmacopceial  Standard.  {Amjune,riS.aruJ' 
15th,  after  1  pint  had  been  withdrawn  from  each  under  ordinary 
conditions. 
The  following  table  shows  the  decrease  in  strength  under  the 
manipulations  described  : 
Per  Cent.  S02* 
Stone  jug,  February  3,  1896   6-67 
May  5,  1896   6*o8 
May  8th.  May  15th. 
Per  Cent.  SOo.      Per  Cent.  S02. 
Bottle  1   5-92     •  5*62 
"     II   5-89     1  5-57 
"     HI.     .  '   5'8o  5-62 
These  results  will  tend  to  show  that  notwithstanding  the  pre- 
cautions directed,  sulphurous  acid,  although  originally  slightly 
above  the  standard  prescribed  by  the  U.  S.  P.,  1890,  will,  upon 
standing  in  vessels  securely  closed  by  corks,  fall  below  thats  tandard, 
and  this  decrease  is  accelerated  by  the  dispensing  of  the  prepara- 
tion. In  warm  weather,  the  evolution  of  gas  is  very  rapid  and  the 
pressure  exerted  will  even  throw  out  the  cork. 
(4)  Aqua  Amnionic?  Fortior  (Stronger  Ammonia  Water.) 
"An  aqueous  solution  of  ammonia  (NH3  =  17-01),  containing  28 
per  cent.,  by  weight,  of  the  gas." — U.  S.  P.,  1890. 
Three  1 -pound  samples  in  their  original  packages  from  different 
sources  (A  and  B)  were,  in  each  case,  freshly  opened,  and  examined 
with  results  as  follows: 
Per  Cent. 
NH3  Per  Cent. 
(A)  January  31st,  average  26-5        (267    and  26 '3) 
May  6th,  average  .  ,  25-54       (25'34>  25-71,  25-57) 
(B)  May  6th,  average  26*61 
In  the  case  of  B,  the  original  bottle  was  closed  with  a  rubber 
stopper.  In  the  case  of  A,  it  was  closed  with  a  cork  stopper,  pro- 
tected by  tinfoil. 
The  deviations  from  the  U.  S.  P.  standard,  it  is  seen,  are  slight,, 
but  distinct,  and  undoubtedly  unintentional. 
(5)  Spiritus  Ammonice. 
"An  alcoholic  solution  of  ammonia  (NH3  =  17-01),  containing  10 
per  cent,  by  weight,  of  the  gas." — U.  S.  P.,  1890. 
Two  quart  specimens  were  examined.  Both  were  contained  in 
glass-stoppered  bottles,  the  glass  stoppers  having  been  previously^ 
