206 
United  States  Pliarmacopoeia. 
Am.  Jour.  Pharm. 
May,  1900. 
Then,  again,  the  Pharmacopoeia  contains  a  number  of  analytical 
methods  which  are  either  impracticable  of  application,  or,  if  ap- 
plied, lead  to  erroneous  conclusions.  In  the  writer's  opinion,  it  is 
far  better  not  to  give  any  directions  than  to  give  a  method  which 
requires  time  and  money  for  execution  and  yet  yields  results  that 
are  worse  than  useless. 
As  an  example,  the  writer  desires  to  call  attention  to  the  direc- 
tions for  estimating  the  moisture  in  wool-fat.  "  When  heated  on  a 
water-bath,  it  finally  leaves  a  residue  amounting  to  not  less  than  70 
per  cent."  If  these  directions  are  followed,  the  oily  portion  and 
the  water  separate,  when  the  temperature  of  the  bath  is  raised  suf- 
ficiently to  melt  the  fatty  product,  and  the  water  sinks  to  the 
bottom,  while  the  fat  floats  on  top.  This  separation  into  layers 
effectually  prevents  the  vaporizing  of  the  aqueous  portion  at  the 
temperature  of  the  water-bath.  Even  at  H5°C.  the  fatty  layer 
retards  the  vaporization  of  the  water  very  materially.  The  writer 
would  not  venture  to  report  on  the  results  obtained  at  the  latter 
temperature  unless  heated  a  very  long  time. 
The  proper  way  to  estimate  the  moisture  in  this  product  is  to 
place  a  given  weight  of  the  article  into  a  tared  evaporating  dish, 
containing  clean,  dry  sand  or  powdered  glass,  and  a  small  glass 
stirring  rod  ;  warm  on  the  water-bath, intimately  mix,  and  occasion- 
ally stir  while  evaporating  on  the  water-bath.  Finally  place  in  an 
air-bath  and  dry  to  constant  weight  at  100°  C.  The  amount  of 
moisture  can  now  be  easily  ascertained  if  the  proper  weights  are  at 
hand. 
Let  us  now  consider  the  position  of  some  chemicals.  Suppose,  for 
example,  one  of  our  States  allows  the  use  of  sodium  benzoate  as  a 
preservative  of  jellies,  mince-meats,  fruits,  etc.,  but  requires  the 
chemical  to  be  of  U.S.P.  quality.  One  manufacturer  claims  that  his 
article  is  U.S.P.  because  he  employs  U.S.P.  goods  from  which  to 
make  it.  Another  maker  says  he  cannot  manufacture  a  U.S.P. 
article  at  the  present  commercial  price.  Yet,  both  use  the  same 
U.S.P.  goods  to  make  their  sodium  benzoate. 
The  reader  perhaps  wonders  where  the  difference  comes  in.  It 
is  this:  one  judges  his  goods  by  the  spirit  of  the  Pharmacopoeia, 
the  other  by  the  letter  of  the  text.  The  requirements  of  both 
sodium  carbonate  and  the  bicarbonate  allow  a  limit  of  chloride  ; 
and  of  course  it  is  expected  (the  spirit)  to  employ  one  of  these  to 
