54 
Resins  and  Relations  to  Ter penes.     {      Jour,  piiann. 
t  \    February,  1913. 
his  historical  work  on  the  common  beet-root.  With  his  discovery 
and  preparation  of  sucrose  from  the  sugar-beet  began  the  first  and 
perhaps  the  greatest  and  most  highly  technical  industry  of  modern 
times.  It  was  likewise  during  the  close  of  this  first  epoch  that 
Pelletier  began  his  classical  work  on  the  alkaloids,  resulting  in 
the  discovery  of  no  less  than  twelve  of  the  important  ones,  includ- 
ing quinine,  strychnine,  and  brucine.  In  fact,  it  was  during  this 
same  epoch  that  nearly  all  of  the  great  families  of  plants  were 
studied  from  the  chemical  point  of  view,  resulting,  in  almost  every 
case,  in  important  discoveries.  Even  the  resins,  which  chemists 
have  until  recently  regarded  as  too  complex  to  deserve  serious 
attention,  were  studied  in  an  industrial  way  and  more  than  thirty 
different  varieties  prepared  and  used  in  the  arts.  But  the  resins 
were  only  one  of  the  many  groups  of  organic  compounds  regarded 
as  too  complex  to  admit  of  other  than  a  study  in  the  most  general 
way,  for  organic  chemistry  had  not  advanced  far  enough  to 
permit  of  a  thorough  chemical  study  of  even  the  simplest  of  the 
organic  substances.  The  adoption  of  the  radical  and  the  ring 
theories  about  the  middle  of  the  last  century,  however,  completely 
changed  the  sphere  of  organic  chemistry  and  synthetic  methods  and 
the  chemical  constitution  of  organic  compounds  became  the  goal 
toward  which  a  large  majority  of  chemists  worked. 
The  adoption  of  the  benzene  ring  theory,  together  with  the 
working  out  of  the  chemical  constitution  of  naphthalene,  pyridine, 
quinoline  and  the  terpenes,  opened  new  fields  in  phytochemistry, 
and  the  first  ten  years  of  labor  after  the  adoption  of  these  new 
theories  showed  amazing  results. 
Structural  and  synthetic  work  in  plant  chemistry  really  began 
in  the  sixties.  In  1869,  Lieberman  startled  the  whole  chemical 
world  by  synthesizing  alizarine,  an  important  vegetable  dye-stuff, 
and  shortly  after  the  alizarine  synthesis,  Baeyer  succeeded  in  build- 
ing up  the  indigo  molecule. 
Following  these  historical  discoveries  came  numerous  pyhto- 
chemical  syntheses,  one  of  the  most  important  being  the  artificial 
preparation  of  vanillin.  Until  Tiemann  had  shown  that  vanillin 
can  be  made  cheaper  in  the  laboratory  than  it  can  possibly  be 
obtained  from  the  vanilla  plant,  chemists,  on  the  whole,  were  some- 
what skeptical  about  the  practicability  of  synthetic  methods  and 
especially  as  to  the  possibility  of  these  synthetic  compounds  sup- 
