Am  Jour.  Pharm.  \ 
Sept.  1,  1872.  J 
Varieties. 
421 
into  the  reducing  portion  of  a  blow-pipe  flame.  In  order  to  avoid  the  difficulty 
resulting  from  the  ready  volatility  of  certain  compounds,  like  those  of  mercury 
and  arsenic,  and  the  ambiguous  colors  of  others,  the  author  recommends  the 
mixture  to  be  placed  in  a  small  glass  tube,  and  to  be  heated  therein.  After  the 
reaction,  which  can  readily  be  followed  by  the  smell  of  the  sulphuretted  hy- 
drogen evolved,  the  fused  mass  will  possess  the  sulphide  colorations  most  clearly. 
It  is  also  recommended  that  the  hyposulphite  be  made  anhydrous  before  use. — 
Ibid. 
The  Use  of  Bromine  in  Analytical  Chemistry. — In  a  former  number  of  the 
"Journal,"  we  took  occasion  to  notice  the  recommendation  of  Mr.  Kammerer, 
who  placed  a  very  high  value  upon  bromine  as  a  substitute  for  chlorine  in  ana- 
lysis. Since  that  time,  to  judge  from  several  publications  upon  the  subject,  it 
appears  to  be  steadily  growing  iu  favor  with  chemists.  Mr.  P.  Waage*  is  the 
last  of  the  writers  on  the  subject,  and,  as  the  result  of  his  experiments,  declares 
bromine  (in  aqueous  or  hydrochloric  acid  solution)  to  be  in  every  respect  more 
suitable  as  an  oxidizing  agent  than  either  nitric  acid,  chlorate  of  potassa  and 
hydrochloric  acid,  or  chlorine.  Each  of  the  last  named  reagents,  while  pos- 
sessing certain  advantages,  have  certain  drawbacks  which  place  a  limit  to  their 
usefulness.  Nitric  acid,  the  usual  oxidizing  agent,  will  only  be  of  service  when 
concentrated,  and  when  in  this  state  cannot  be  used  in  platinum  vessels  on 
account  of  the  small  quantities  of  chlorine  which  it  generally  contains,  and 
must  be  kept  from  contact  with  organic  matter  like  filter  paper,  if  subsequent 
precipitations  are  to  be  made.  Chlorate  of  potassa  will  only  act  when  in  pres- 
ence of  somewhat  concentrated  hydrochloric  acid  and  a  difficulty  is  always 
experienced  in  drawing  out  the  last  portions  of  chlorine,  which  necessitates  at 
times  repeated  addition  of  hydrochloric  acid.  The  use  of  chlorine  is  attended 
with  the  objection  of  the  arrangement  of  an  apparatus  for  every  oxidation,  and 
the  fact  that  only  a  small  quantity  of  the  gas  can  be  dissolved  in  water,  ren- 
dering the  employment  of  much  liquid  necessary.  Bromine,  however,  seems  to 
be  free  from  these  drawbacks,  and  hence  to  be  deserving  of  a  place  as  a  stand- 
ard oxidizing  reagent  in  the  analytical  laboratory.  The  author  recommends 
its  employment,  either  pure  or  as  bromine  water  (which  can  be  obtained  with 
two  to  three  per  cent,  of  bromine),  or  in  hydrochloric  acid  solution,  containing 
about  15  per  cent,  of  bromine.  The  color  of  the  element  is  a  good  indicator 
by  which  excess  maybe  avoided  and  its  low  boiling  point  permits  it  to  be 
driven  off  with  little  difficulty.  Bromine  water  is  without  action  on  platinum 
(except  in  presence  of  nitric  acid),  and  is  without  action  on  filter  paper.  As 
an  agent  for  the  oxidation  of  sulphur,  sulphydric  acid  and  metallic  sulphides 
as  in  the  solution  of  iron  or  copper  pyrites,  mispickel,  and  precipitated  sulph- 
ides, the  opinions  of  those  who  have  worked  with  it,  express  nothing  but  the 
most  complete  satisfaction. — Ibid. 
*Chem.  News,  xxr,  282. 
