55^  Development  of  the  Chemical  Arts.  {^'"•fcsjt"™' 
twelfth.  This,  as  has  been  shown  above,  amounts  to  the  transforma- 
tion of  one-fourth  of  the  oxygen  present  into  ozone. 
An  instrument  of  this  kind,  of  a  simple  construction,  was  described 
by  Werner  Siemens*  in  1857.  Brodief  has  recently  defended  the 
claims  of  this  eminent  physicist  in  opposition  to  supposed  recent  in- 
ventors, especially  Houzeau.  Wills  J  gave  the  instrument  a  less  fragile 
form,  and  with  this  modification  it  has  been  recently  introduced  into 
trade  by  the  English  mechanicians,  Tisley  and  Spiller.||  It  has  the 
advantage  that  it  can  be  cooled  by  the  passage  of  a  current  of  water. 
As  Siemens  recommended  the  application  of  the  thinnest  possible  glass^ 
it  remains  to  be  decided  whether  the  more  solid  form  may  not  involve 
a  reduction  of  the  yield  of  ozone. 
Siemen's  instrument  consists  essentially  of  two  concentric  tubes  of 
glass,  the  inner  tube  being  lined  with  tinfoil  within,  and  the  exterior 
coated  with  the  same  material  without.  The  inner  tube  is  closed  at 
one  end,  and  is  sealed  to  the  outer  tube  in  such  a  manner  that  an  inter- 
val remains  between  them.  The  outer  tube  is  drawn  out  at  one  end  to 
a  thin  junction  piece,  and  a  similar  one  is  fused  to  it  at  the  other  end. 
Oxygen  circulates  in  the  interval.  If  the  wire  ends  of  the  Ruhm- 
korff's  apparatus  are  brought  in  contact  with  the  tinfoil  coating  of  the 
tubes,  the  intervening  space  becomes  luminous,  and  the  oxygen  present 
is  ozonized.  Rumine§  in  England,  and  Low  in  France,^  patented, 
in  1872,  a  process  for  obtaining  ozone  by  blowing  cold  air  into  the 
Bunsen  flame.  There  is  no  information  as  to  the  results  of  this 
process. 
A  patent  obtained  in  England,  and  specified  far  from  clearly,  for  ob- 
taining ozone  by  boiling  seaweed,**  may  be  mentioned  as  a  curiosity, 
and  also  the  credulity  with  which  ozone-baths,  prepared  in  this  manner, 
find  a  ready  sale,  in  spite  of,  or  perhaps  rather  on  account  of,  their 
high  price.  It  appears  at  any  rate  that  an  industrial  method  of  obtain- 
ing ozone  is  hitherto  an  unfulfilled  desideratum. 
Only  the  highest  branch  of  industry,  that  in  which  justly  no  price 
is  considered  too  high,  as  its  object  is  health,  to  wit,  medicine,  has 
*  Siemens,  "  Pogg.  Ann.,"  cii.,  120. 
fBrodie,  "Nature,"   Feb.  18,  1874. 
X  Wills,  "Ber.  Chem.  Ges.,"  vi.,  769. 
II  "  Nature,"  viii  (1873)  ^4^- 
§  Rumine,  "  Ber.  Chem.  Gesell.,"  v.,  123. 
\  Low,  "  Ber.  Chem.  Gesell.,"  v.,  740. 
■*^«Berl.  Chem.  Gessel.,"  v.,  543. 
