Am'Mayr'i9i5aim* }    Some  Studies  on  the  Oxy-pinenes.  207 
According  to  this  supposition  auto-oxidation  takes  place  by  direct 
/O 
addition  of  a  molecule  of  oxygen  to  the  pinene  Ci0Hi6<^  |  • 
\0 
It  has  already  been  referred  to  how  Engler  and  his  helpers  tried 
to  use  this  hypothesis  in  explaining  the  oxidation  phenomena  of 
pinene,  but  were  baffled  by  the  different  absorption  of  "  active  "  and 
ordinary  oxygen  at  different  temperatures. 
That  ozone  and  peroxide  of  hydrogen  could  not  exist  together 
was  definitely  proved  by  Schoenbein  as  early  as  1879,  who  showed 
that  in  that  case  the  reaction  03  +  H202  =  H20  +  20,  necessarily 
must  take  place  {Ann.,  vol.  196).  H.  Schiff,  in  two  exceptionally 
thorough  articles  (Ber.,  vol.  16,  and  Chem.  Zeit.,  vol.  20),  has  set 
beyond  all  doubt  that  by  air  oxidation  of  turpentine  an  aldehyde  of 
pinene  is  formed,  but  he  is  in  doubt  if  to  give  it  the  formula 
G10H16O3  or  C10H16O4.  He  also  proves  that  the  property  of  turpen- 
tine to  absorb  oxygen  and  give  it  off  again  to  other  substances  has 
nothing  whatever  to  do  with  the  presence  of  water. 
Although  ozone  had  been  known  as  a  powerful  oxidizer  ever  since 
its  discovery,  1840,  there  is  very  little  mentioned  about  it  in  scientific 
literature  in  this  connection — at  least  as  a  direct  oxidizer.  Adolphe 
Renard,  in  1895,  produced  what  he  called  ozo-benzol  (Compt.  rend., 
vol.  120)  from  direct  action  of  ozone  on  benzol,  and  this,  undoubtedly 
was  a  true  ozonide,  but  it  attracted  no  attention  at  the  time. 
Instead  of  following  this  clue  to  what  an  ozonide  is,  a  bitter  con- 
troversy arose — as  has  been  previously  stated — over  the  question  of 
in  what  form  "  active  "  oxygen  existed  on  oxy-pinenes — some  holding 
stubbornly  to  the  theory  that  it  was  there  as  ozone,  and  others  with 
equal  tenacity  maintaining  that  it  could  exist  only  in  the  form  of  a 
peroxide. 
It  was  only  after  Dr.  Karl  Harries,  professor  of  chemistry  at  the 
University  of  Kiel,  took  up  the  investigation  that  the  question  was 
satisfactorily  and  definitely  settled,  and  to  him  and  his  disciples  and 
followers  is  due  the  greatest  credit  for  our  present  knowledge  of  the 
ozonides  and  the  oxy-pinenes. 
Already  in  1903,  in  an  article  in  Berichte  der  deutschen  chem- 
ischen  Gesellschaft  (vol.  36,  2,  p.  1933),  Harries  begins  a  series  of 
researches  on  the  oxidation  of  ozone.  In  this  article  he  only  calls 
attention  to  the  fact  that  alcohols  oxidized  by  ozone  form  aldehydes ; 
so,  for  instance,  does  methyl  alcohol,  when  oxidized  by  ozone,  form 
formaldehyde  in  water  solutions. 
