426 
A  tmospheric  Ozone. 
(Am.  Jour.  Pharm. 
I  September,  1900. 
apparatus  was  placed  on  the  veranda,  while  in  March  it  was  located 
in  the  yard,  at  least  50  feet  from  the  house.  This  difference,  though 
small,  had  an  undoubted  influence  on  the  circulation  of  air  and  is 
important  in  explaining  the  smaller  amounts  of  ozone  found  in  Feb- 
ruary. In  Covington,  as  elsewhere,  March  is  the  most  windy 
month  of  the  year.  In  February  the  air  was  comparatively  still, 
but  our  notes  show  that  on  the  27th — date  of  maximum  ozone  of 
the  month — it  was  quite  windy. 
The  absorption  of  a  definite  amount  of  air  was  accomplished  by 
siphoning  a  definite  quantity  of  water  from  an  air-tight  container, 
fitted  with  a  rubber  cork,  through  which  passed  two  glass  tubes, 
one  serving  as  the  siphon,  the  other  to  admit  air.  To  the  inlet  tube 
was  attached  an  appropriate  potash  bulb — Mohr's  or  Liebig's — 
preference  being  given  the  former. 
As  containers,  a  26-gallon  oak  barrel  and  a  iO-gallon  tin 
can  were  employed,  the  latter  proving  more  satisfactory,  because 
more  convenient  to  handle  and  less  prone  to  leakage.  The  meas- 
urement of  the  siphoned  water  (of  course  the  volume  of  air  admitted 
was  identical  to  that  of  the  water  removed)  was  accomplished  in  two 
ways:  (1)  By  measuring  the  amount  actually  siphoned  off;  (2)  by 
placing  a  definite  quantity  of  water  in  the  container  and  then  meas- 
uring the  quantity  left  after  the  siphon  ceased  to  run.  Both  methods 
gave  practically  identical  results,  and,  as  the  latter  was  more  conve- 
nient, it  was  usually  employed. 
Each  solution  was  directly  transferred  from  its  bottle  to  the 
absorption  bulb  by  suction,  the  traces  of  the  solution  clinging  to 
the  outer  lip  of  the  bulb  being  carefully  washed  back  into  the  bottle 
with  distilled  water.  The  bulb  was  immediately  attached  to  the 
siphoning  apparatus  by  a  rubber  joint,  the  flow  of  air  regulated  to  . 
100-150  bubbles  a  minute  and  continued  until  the  desired  amount 
had  passed  through  the  solution. 
As  the  value  of  both  methods  of  assay — the  iodide  and  the 
arsenite — has  been  assailed  on  the  ground  that  similar  oxidizing 
effect  might  result  from  the  acid  constituents  of  the  atmosphere,  it 
was  deemed  expedient  in  some  of  the  tests  to  first  pass  the  air 
through  a  solution  of  soda.  Such  tests  are  marked  with  an  aster- 
isk in  the  appended  tables,  and  it  will  be  noticed  that  our  figures 
show  that  the  criticism  is  groundless. 
After  the  air  had  passed  through  the  solution,  the  contents  of  the 
