AD4cJembe?,1i905.1'}      Inorganic  Chemistry  of  the  U.S. P.  561 
dioxide  are  dissolved  in  a  mixture  of  50  c.c.  of  tenth-normal  oxalic 
acid  V.  S.  and  3  c.c.  of  sulphuric  by  heating  on  a  water  bath,  the 
resulting  solution  diluted  with  100  c.c.  of  warm  water  and  the  excess 
of  oxalic  acid  V.  S.,  found  by  retitration  with  tenth-normal  potassium 
permanganate  V.  S.  not  more  than  13  c.c.  of  which  should  be  re- 
quired. The  reaction  may  be  expressed  by  the  equation 
MnQ2  +  (HoCA  +  2H2)  O  4-  H2S04  =  MnS04  +  4H20  +  2CO, 
Potassii  Bichromas  is  now  Potassii  Dichromas  (K2Cr207). — This 
change  is  a  perfectly  proper  one,  the  new  name  being  more  in  accord 
with  our  present  views  regarding  chemical  nomenclature.  A  bi  salt 
is  one  in  which  part  of  the  hydrogen  of  the  acid  is  replaced  by  a 
metal,  thus  a  bi  salt  contains  an  atom  or  more  of  hydrogen,  which 
this  salt  does  not  contain.  Looked  upon  as  potassium  chromate, 
K2Cr04  -f  Cr03,  it  may  be  properly  called  dichromate.  The  tests 
are  the  same  as  in  the  old  Pharmacopoeia,  though  when  used  as  a 
test-solution  a  quarter  degree  of  purity  is  required.  The  salt  should 
contain  99  per  cent,  of  pure  potassium  dichromate. 
Sodii  Hyposulphis  is  now  called  Sodii  Thiosulphas. — This  salt  has 
long  been  erroneously  called  hyposulphite ;  it  is  a  powerful  reducing 
agent  and  is  employed  in  photography  to  dissolve  out  of  negatives 
the  unaffected  haloid  salts  of  silver,  thus  "  fixing  "  the  picture.  It 
is  the  "  hypo  "  of  the  photographer.  Our  present  nomenclature 
would  represent  hyposulphite  of  sodium  by  the  formula  Na2S02, 
whilst  the  salt  under  discussion  is  a  salt  of  thiosulphuric  acid 
(H2S203)  and  its  chemical  formula  is  Na2S203.  This  salt  crystallizes 
with  5  molecules  of  water,  and  should  contain  not  less  than  98  per 
cent,  of  pure  salt.  The  qualitative  tests  are  the  same  as  those  given 
in  the  old  Pharmacopoeia,  with  the  exception  of  the  time-limit  test 
for  heavy  metals  and  the  modified  Gutzeit's  test  for  arsenic.  The 
assay  method  is  the  same,  except  that  a  larger  quantity  of  the  salt  is 
taken  for  analysis  and  the  use  of  starch  as  an  indicator  is  discarded. 
Sodii  Sulphocarbolas  is  now  called  Sodii  Phenol sulphon  as, 
NaC6H504S  -f  2H20. — It  should  contain  not  less  than  99  per  cent, 
of  pure  sodium  paraphenolsulphonate  (C6H4(OH)S03Na).  The  tests 
are  the  same  as  before,  with  the  exception  that  metallic  impurities 
are  detected  by  the  time-limit  test,  and  the  tests  for  sulphate  and 
for  chloride  are  omitted. 
Zinci  Valerianas  is  now  called  Zinci  Valeras,  Zn(C5H902)2  -f-  2H20. 
— The  tests  for  impurities  comprise  the  time-limit  test  for  the  detec- 
