Am.  Jour.  Pharro.  1 
September,  1900.  J 
Atmospheric  Ozone. 
423 
ATMOSPHERIC  OZONE. 
By  R.  A.  Hatcher,  M.D.,  and  H.  V.  Arny,  Ph.D. 
Having  made  some  quantitative  estimations  of  atmospheric  ozone 
in  the  neighborhood  of  Covington,  La.,  intended  for  use  in  an  article 
upon  that  place  as  a  health  resort,  the  literature  upon  the  subject 
proved  such  a  surprise  to  the  authors  that  a  separate  article  was 
deemed  timely. 
Though  the  "  electrical  odor  "  which  we  attribute  to  ozone  had 
long  been  known,  and  Van  Marum  had,  in  1785,  passed  a  current 
through  oxygen,  producing  a  substance,  some  of  the  characteristics 
of  which  he  studied,  to  Schonbein  is  due  the  credit  of  stimulating 
research  upon  this  difficult  subject. 
Dr.  Andrews  (Phil.  Trans.,  1855-56,  1-3)  showed  that  ozone  was 
denser  than  oxygen,  and,  in  the  following  year,  Odling  gave  its 
molecular  formula  as  03. 
Soret  (Ann.  Chem.,  XIII,  257)  confirmed  this  in  1865  by  remov- 
ing one-third  of  the  oxygen  from  ozone  with  potassio-mercuric 
iodide,  while  he  removed  all  the  ozone  from  its  admixture  with  air, 
by  means  of  oil  of  turpentine. 
Sir  Benj.  Brodie  further  confirmed  Odling's  formula  by  showing 
that  three  volumes  of  oxygen  are  condensed  to  two  volumes  of  ozone, 
and  that  ozone  has  one  and  one-half  times  the  density  of  oxygen. 
Several  methods  have  been  suggested  for  the  detection  and  esti- 
mation of  ozone.  Schbnbein's  paper  is  prepared  by  making  a 
solution  of  potassium  iodide  in  gelatinous  starch  paste,  spreading 
this  upon  paper  and  drying,  this  being  protected  from  light  and 
air. 
Houzeau  (Pogg.  Ann.,  CIX,  180),  whose  testimony  is  corroborated 
by  Gianneti  and  Volta  (Gaz.  Chun.  Ital.,  IV,  421),  found  Schonbein's 
paper  unreliable,  and  recommended  (Ann.  Chim.  et  Phys.,  XXVII, 
5)  red  litmus  paper  treated  with  a  neutral  solution  of  potassium 
iodide,  ozone  liberating  potassium  hydrate  and  changing  color  of 
paper  tu  blue.  He  also  suggested  (Compt.  Rend.,  XLIII,  38,  and 
LII,  527)  the  use  of  a  solution  of  potassium  iodide  for  quantita- 
tive estimation,  the  ozone  converting  a  part  of  the  iodide  into 
iodate,  hydrochloric  acid  being  added  to  liberate  the  iodine,  which 
is  estimated  in  the  usual  manner  with  sodium  thiosulphate. 
Hartley  (Watt's   Diet.)   recommended  potassium   arsenite  for 
