510 
OZONE  AND  THE   VOLATILE  OILS. 
Crumbs  of  the  gum  resin  boiled  with  the  indigo  solution  yielded  a 
pale  blue  milky  mixture,  which  by  exposure  to  the  sun's  rays  soon 
became  white,  but  remained  milky. 
8.  It  is  stated  in  the  U.  S.  Dispensatory  that  tincture  of  galba- 
num  becomes  milky  on  the  addition  of  water,  but  yields  no  preci- 
pitate. This  is  true  for  a  certain  length  of  time,  but  after  fifteen 
or  twenty  hours  a  perceptible  deposit  is  apparent.  The  action  of 
the  indigo  solution  was  much  more  obvious  in  this  way,  for  in  an 
hour  after  the  addition  there  was  a  well  defined  precipitate,  which 
left  the  liquid  semi-transparent. 
9.  I  boiled  some  crumbs  of  galbanum  in  water,  in  a  Florence 
flask,  until  the  peculiar  odor  of  the  gum  resin  was  diffused  through 
the  laboratory  and  adjoining  rooms.  The  mouth  of  the  flask  was 
loosely  corked,  and  during  the  whole  of  the  ebullition  a  strip  of 
iodized  paper  was  kept  suspended  in  the  vessel.  No  discoloration 
of  the  paper  appeared  even  after  an  hour's  exposure  to  the  vapor, 
nor  in  twenty-eight  hours  after  cooling. 
10.  Slips  of  iodized  paper  were  suspended  in  the  bottles  con- 
taining more  or  less  of  the  following  oils,  and  other  substances. 
The  times  at  which  decomposition  of  the  iodide  took  place  are  at- 
tached to  the  respective  oils: 
Oil  of  Lemon,  blue  in  five  minutes,  black  in  ten  minutes. 
Oil  of  Cinnamon,  slightly  colored  in  four  minutes,  blue  in  twelve 
minutes. 
Oil  of  Lavender,  pale  red  in  ten  minutes. 
Oil  of  Fir,  Turpentine,  Tansey,  and  Cubebs,  slightly  brown  m 
ten  minutes. 
Oil  of  Amber  and  Rosemary,  light  purple  in  fifteen  minutes. 
Oil  of  Croton,  pink  in  23  minutes. 
Oil  of  Peppermint,  light  brown  in  twenty-five  minutes. 
Oil  of  Savine,  slight  tinge  in  thirty  minutes. 
Oil  of  Caraway,  Wintergreen,  Sassafras,  Fennel,  Cloves,  Spear- 
mint, Bergamot,  and  Wormseed,  (Baltimore) — no  change  in  an 
hour,  but  after  two  to  thirteen  hours  the  paper  was  colored  in  the 
sassafras,  wormseed,  &c,  bottles. 
Tincture  of  Castor,  and  Camphor — no  effect. 
11.  A  broad  slip  of  paper  was  prepared  with  the  solution  of 
iodide  of  potassium  in  starch,  thoroughly  dried,  and  the  names  of 
various  volatile  and  fixed  oils,  and  some  tinctures,  written  on  it7 
