Ambers}      Inorganic  Chemistry  of  the  U.S. P.  515 
whereas  in  the  former  U.S. P.  a  test  for  calcium  was  described.  An 
innovation  is  the  "  Time-limit  Test  for  Heavy  Metals,"  which  takes 
the  place  of  the  specific  tests  for  lead  and  for  iron  of  the  U.S.P.  of 
1890.    Arsenic  is  detected  by  the  "  Modified  Gutzeit's  Test." 
The  assay  consists  of  a  simple  neutralization,  using  normal  potas- 
sium hydroxide  v.  s.  in  the  presence  of  methyl  orange  as  indicator  ; 
phenolphthalein  was  formerly  used  as  indicator.  The  permanganate 
method  for  assaying  this  acid,  described  in  the  U.S.P.  of  1890,  has 
been  dismissed  as  unnecessary.  Acidum  hypophosphorosum  dilutum 
is  made  from  the  stronger  acid  by  dilution.  The  stronger  acid  is 
the  more  stable,  hence  its  introduction  is  to  be  regarded  as  a  wise 
step. 
Ammonii  Salicylas,  Ammonium  Salicylate  (NH4C7H503). — This 
salt  is  so  little  used  that  its  introduction  to  the  U.S.P.  seems  an 
unnecessary  one. 
Bismuthi  Subgallas,  Bismuth  Subgallate. — "  Bismuth  subgallate 
should  yield  not  less  than  52  per  cent,  nor  more  than  57  per  cent, 
of  pure  bismuth  oxide  "  (Bi2Os).  This  salt  is  of  somewhat  variable 
chemical  composition  and  therefore  no  chemical  formula  for  it  is 
given  in  the  Pharmacopoeia.  It  is  approximately  Bi(OH)2C7H505. 
The  wisdom  of  the  introduction  of  this  salt  must  be  apparent  to 
all.  It  has  been  widely  used  for  a  long  time  under  the  trade  name 
of  dermatol  and  has  been  found  a  highly  valuable  remedy  both  for 
external  and  for  internal  use.  It  is  official  in  the  German  Pharma- 
copoeia. Satisfactory  physical  and  chemical  tests  for  identity  are 
given  in  the  U.S.P.  as  well  as  descriptions  of  tests  for  impurities, 
free  gallic  acid,  nitrate,  and  arsenic. 
The  gravimetric  process  for  its  assay  consists  in  thoroughly 
igniting  1  gramme  of  the  bismuth  subgallate  in  a  porcelain  crucible  ; 
it  at  first  loses  water,  then  chars,  and  finally  leaves  a  yellowish  resi- 
due ;  this,  when  cool,  is  treated  with  5  c.c.  of  nitric  acid,  added  drop 
by  drop  and  warming  until  complete  solution  is  effected,  the  result- 
ing solution  of  nitrate  is  evaporated  to  dryness,  the  residue  converted 
by  ignition  into  bismuth  oxide ;  this  should  weigh  not  less  than 
0*52  gramme  nor  more  than  0  57  gramme. 
Bismuthi  Subsalicylas,  Bismuth  Subsalicylate. — This  "  should  yield 
not  less  than  62  nor  more  than  64  per  cent,  of  bismuth  oxide."  It 
is  assayed  in  exactly  the  same  manner  as  the  foregoing.  It  is  also 
official  in  the  German  Pharmacopoeia.   The  tests  for  identity  are  the 
