COMBUSTIBILITY  OF  POWDERED  IRON. 
255 
globules  were  soluble  in  hydrochloric  acid,  the  yellow  insoluble; 
the  solution  on  evaporation  yielded  feathery  needles  and  rhom- 
bic prisms,  re-action  of  sub-oxide  and  oxide  of  tin.  The  pre- 
sence of  tin  was  likewise  proven  before  the  blowpipe  upon  char- 
coal, and  with  phosphate  of  soda  and  ammonia,  the  above  dis- 
tilled water  after  evaporation  gave  the  re-action  of  tin,  with 
ammonia,  ferrocyanuret  of  potassium,  and  hydrosulphuric  acid, 
caustic  potassa  evolved  ammonia,  but  not  a  trace  of  copper 
could  be  detected. 
All  his  other  experiments  proved  the  presence  of  tin  in  dis- 
tilled waters  from  the  tin  worm,  whether  this  was  new  or  had 
been  used  for  a  considerable  time.  The  author  likewise  thinks, 
the  quantity  of  ammonia  in  distilled  water  larger  than  in  pump 
water,  which  he  analyzed,  and  which  contained  only  traces  of 
it.  He  supposes  some  water  might  be  decomposed  by  the  tin,  this 
metal  uniting  with  the  oxygen,  while  the  hydrogen  in  the  nascent 
state  with  the  nitrogen  of  atmospheric  air,  forms  ammonia, (?) 
The  slimy  precipitate  in  distilled  medicinal  waters  contains 
nearly  all  the  tin,  and  the  slime  which  is  often  observed  on  the 
inside  of  a  tin  head  or  worm,  and  which  has  a  greasy  touch,  is 
tin.  In  conclusion,  the  author  draws  attention  to  the  traces  of 
tin  sometimes  found  in  mineral  waters,  and  suggests  they  might 
be  owing  to  the  tin  of  the  distilled  water  employed. — Arcliiv  d. 
Pharmacie,  1858,  Aug,  156-163.  J.  M.  M. 
COMBUSTIBILITY  OF  POWDERED  IRON. 
Professor  Magnus  of  Berlin,  at  the  last  Medical  and  Philo- 
sophical Convention,  at  Karlsruhe,  has  drawn  attention  to  a 
curious  behaviour  of  powdered  iron.  It  is  well  known,  that  iron 
reduced  by  hydrogen  is  very  combustible,  and  may  be  ignited 
by  contact  with  a  flame,  when  it  rapidly  burns  to  peroxide. 
Powdered  iron  obtained  from  filings  or  in  any  other  similar  way, 
is  under  ordinary  circumstances  not  inflammable ;  such  iron 
made  by  a  mechanical  process  on  a  large  scale  in  Tyrol,  for  me- 
dical and  pharmaceutical  purposes,  has  repeatedly  been  sold  for 
iron  reduced  by  hydrogen ;  as  it  is  very  subtile,  the  fraud  can 
only  be  detected  by  its  not  taking  fire  on  being  approached  with 
