260        METHOD  OF  DEODORIZING  IMPURE  HYDROGEN,  ETC. 
3.  In  not  passing  off  so  quickly  through  the  kidneys. 
4.  In  not  producing  gastro-enteritic  and  vesical  irritation. 
5.  In  being  inexpensive  and  easily  prepared,  and  therefore 
not  liable  to  adulteration. 
6.  In  being  nearly  tasteless,  and  therefore  readily  taken,  even 
by  children ;  and  admitting  of  a  variety  of  combinations  in  ex- 
temporaneous prescription. 
Dr.  Pidduck  entered  somewhat  at  length  into  the  therapeutic 
effects  of  this  form  of  iodine  in  the  treatment  of  disease  in  those 
intractable  cases  of  neuralgia  caused  by  metallic  poisons,  such  as 
mercury,  lead  and  copper,  for  which  purpose  it  had  been  exten- 
sively prescribed,  in  small  doses  of  \  of  a  grain,  at  the  Blooms- 
bury  Dispensary  during  the  last  two  years,  with  marked  good 
effect.  This  being  foreign  to  the  objects  of  the  Society,  is 
omitted  in  this  notice. — London  Pharm.  Journ. —  Trans. 
Pharm.  Society. 
ON  A  SIMPLE  METHOD  OF  DEODORIZING  IMPURE  HYDROGEN 
AND  CARBONIC  ACID  GASES. 
By  John  Stenhouse,  LL.  D.,  F.  R.  S. 
When  hydrogen  gas  is  prepared  by  acting  with  dilute  sulphuric 
or  hydrochloric  acids  upon  commercial  zinc,  it  has  always  a 
slightly  disagreeable  odor,  arising,  as  is  well  known,  from  the 
presence  of  a  small  quantity  of  a  liquid  hydrocarbon,  resembling 
impure  naphtha  in  its  properties.     The  hydrogen  gas  made  with 
malleable  iron  has  a  still  more  disagreeable  odor,  arising  from 
larger  quantities  of  a  similar  hydrocarbon,  together  with  traces 
of  sulphuretted,  phosphoretted,  and  sometimes  even  of  arse- 
niuretted  hydrogen.    So  offensive  is  this  odor,  that  hydrogen 
gas  is  very  seldom  prepared  from  malleable  iron,  and  almost 
never  from  cast  iron,  which  yields  still  more  of  these  impurities, 
though  both  malleable  and  cast  iron  are  immensely  cheaper 
sources  of  hydrogen  than  zinc.    Scraps  of  malleable  iron,  from 
their  more  ready  solubility  in  acids,  are  better  adapted  for  pre- 
paring hydrogen  gas  than  cast  iron.    By  the  following  simple 
arrangement,  however,  of  passing  the  impure  hydrogen  through 
a  short  column  of  coarsely-powdered  charcoal,  or,  in  other  words, 
