392  The  U.S. P.  Inorganic  Chemicals.      {Am£u^!i mfw* 
No.  1=10-99  to  10-96  per  cent.  NH3  and  89-07  per  cent,  of  sali- 
cylic acid;  moisture,  o-n  per  cent,  (traces  of  phenol). 
No.  2=10-93  to  IO'95  Per  cent-  NH8  and  88-36  per  cent,  of  sali- 
cylic acid  ;  moisture,  0-16  per  cent. 
No.  3=10-16  per  cent.  NH3. 
Theory=n  per  cent,  of  NH3  and  89-00  per  cent,  of  salicylic  acid, 
corresponds  to  anhydrous  salt. 
Theory=io*39  per  cent,  of  NH3  and  84-12  per  cent,  of  salicylic 
acid,  salt  with  half  a  molecule  of  H20. 
All  the  salts  contain  necessarily  a  slight  excess  of  salicylic  acid. 
A  98  per  cent,  salt  as  adopted  by  the  U.S. P.  allows  2  per  cent, 
for  free  salicylic  acid  and  moisture. 
Antimony  Oxid. — Very  little  if  any  of  this  chemical  is  made  in 
this  country,  all  being  imported.  Little  if  nothing  is  known  of  its 
origin  and  quality.  The  analysis  would  indicate  that  the  samples, 
although  from  distant  sources  in  this  country,  were  obtained  from 
the  same  parties  abroad.  These  were  found  to  be  insoluble  in 
acids,  alkalies  and  organic  acids.  Evidently  this  antimony  oxid 
consists  of  a  mixture  of  various  antimonic  acids.  Such  a  product  is 
of  but  little  medicinal  use  and  since  no  standards  could  be  drafted 
with  which  it  might  possibly  comply,  it  is  better  out  of  the  Phar- 
macopoeia than  in : — 
Per  cent.  Sb.  Per  cent.  Sb. 
Eastern  Sample  5074     Theory,  Sb406  contains   ....  83*36 
Western  Sample  ........  50.86  "     Sb205  contains   ....  75*02 
Arsenic  Trioxid. — The  formula  As406  which  is  used  by  some 
chemists,  is  based  on  the  vapor  density  taken  between  5000  and 
700°  C,  while  at  17700  C.  and  above,  the  density  corresponds  to 
the  old  formula  As203.  The  determination  of  the  solubility  of 
arsenous  oxid  is  very  unsatisfactory ;  aside  from  temperature,  time 
plays  the  most  important  part;  when  macerated  in  water  at  150  C. 
for  one  day,  the  solubility  was  1  in  6122  parts  of  water;  for  two 
days,  1  in  4835  parts.  Comey  in  his  work  on  solubilities  gives  the 
following  interesting  table  : — 
Crystalline.  Amorphous, 
i  hour,    100  parts  water  dissolve  0-023  1*58 
12  hours, 
24  hours, 
1  week, 
3  weeks, 
2%  years, 
0-  360  3-36 
o*9S6  3-3o6 
1-  67  1.76 
1-776  1*713 
1-710  1707 
