^sSt*!,  w™'}  Preliminary  Note  on  Ozone.  399 
Oxygen  obtained  by  either — 
(a)  .  Heating  mercuric  oxide,  and  passing  the  resulting  gas  through 
strong  and  pure  potassic  hydrate  (to  absorb  any  nitrous  fumes) ; 
(b)  .  Acting  upon  potassic  dichromate  with  hydric  sulphate  ; 
{<?).  Acting  upon  potassic  permanganate  with  hydric  sulphate;  or, 
(d).  Heating  native  or  artificial  manganic  dioxide  ; — liberated  io- 
dine from  potassic  iodide,  forming,  when  starch  was  present,  the  blue 
iodide.  In  short,  from  every  source  I  have  tried,  the  oxygen  pro- 
duced never  lacked  these  properties.  Of  course  contact  of  the  gas 
-examined  with  organic  matter  was  avoided  as  far  as  possible. 
Thus  in  (a)  the  tube  containing  the  mercuric  peroxide  was  drawn 
out,  and  bent  twice  at  right  angles,  and  then  passed  into  a  tube  hold- 
ing the  potassic  hydrate,  the  column  depth  of  which  was  in  every  ex- 
periment more  than  four  inches,  (b)  and  (c)  are  readily  performed 
in  open  test-tubes,  placing  at  the  mouths  of  the  tubes  the  paper  soaked 
in  the  potassic  iodide  and  starch  mixture. 
But  acting  upon  potassic  permanganate  with  hydric  sulphate  re- 
quires care,  for  (as  is  well  known)  if  the  mixture  be  heated,  vapors  of 
permanganic  acid  are  evolved  and  detonations  occur.  I  purposely 
obtained  these  detonations  twice  by  placing  tubes  containing  the  mix- 
ture in  a  steam-bath.  The  contents  of  the  tubes  smelt  strongly  of 
ozone  afterwards,  just  like  the  fishy  odor  obtained  by  the  passage  of 
olectric  sparks  through  moist  air  or  oxygen  ;  and  on  holding  a  piece 
of  iodide  paper  over  the  mouths  of  the  tubes,  iodine  was  rapidly  lib- 
orated. 
In  (t?),  the  manganic  dioxide  may  be  heated  to  bright  redness,  and 
yet  the  vapors  evolved  contain,  or  in  some  way  produce,  the  agent  al- 
luded to  before.  This  is  remarkable,  considering  that  ozone  is  de- 
stroyed instantaneously  at  300°  C,  and  slowly  at  much  lower  tem- 
peratures. However,  at  present,  I  have  no  proof  to  offer  that  it  is 
ozone ;  the  moisture  on  the  iodide  paper  may  share  in  the  reactions 
which  occur. 
I  have  ventured  these  statements  in  the  belief  that  the  facts  stated 
are  not  generally,  if  at  all,  known.  If  they  are  known,  my  experi- 
ments merely  confirm  them,  and  if  they  are  not  known  and  explained, 
I  hope  to  be  able  to  show  by  a  series  of  experiments  which  I  am  now 
making,  not  only  the  effects  but  also  the  causes. 
St  Ann's,  St.  Helens,  Lancashire,  May  14,  1872. 
— Qhem.  News,  May  24,  1872. 
