Am.  Jour.  Pharm.  \ 
January,  1900.  J 
Constitution  of  the  Alkaloids. 
15 
diethyl-  and  dimethylurea,  just  as  Wohler  had  previously  obtained 
urea  from  cyanic  acid.  When  he  then  treated  these  alkyl-ureas  or 
simply  the  cyanic  esters  themselves  with  caustic  potash,  he  obtained 
the  substituted  ammonias  themselves  as  strong  alkaline  limpid 
liquids  : 
HCNO  +  2KOH  =  K2C03  -h  NH3 
CH3CNO  +  2KOH  =  K2C03  +  NH2CH3 
C2H5CNO      +  2KOH  —  K2C03  +  NH2C2H3 
C0NH.2  +  2K0H  ^  K2C03  4-  2NH3 
CO  nh*.CH3  +  2K0H  =  K*C0*  +  2NH2.CH3 
CO  NH!c2Hg  +  2K0H  =  K2C°3  +  2NH2-C2H5 
This,  then,  proved  conclusively  the  nature  of  the  substituted  am- 
monias, and  that,  in  all  probability,  all  alkaloids  were  ammonia  in 
which  one  or  more  of  the  hydrogen  atoms  had  been  replaced  by 
oxygenated  or  non-oxygenated  radicals.  The  next  step  in  the 
development  of  the  constitution  of  the  alkaloids  was  the  result  of 
Gerhardt's  distillation  -of  quinine,  cinchonine  and  strychnine  with 
caustic  potash,  whereby  he  obtained  quinoline,  and  of  Anderson's 
study  of  the  so-called  Dippel's  oil,  an  oil  obtained  from  the  destruc- 
tive distillation  of  animal  matter,  and  also  called  "Oleum  animale 
Dippelii,"  which  yielded  him  pyridine,  picoline,  lutidine  and  other 
volatile  basic  oils,  and  of  bone  oil,  which  yielded  the  same  products. 
Some  chemists  now  held  that  possibly  alkaloids  were  not  at  all  deriv- 
atives of  ammonia,  but  might  be  derivatives  of  some  of  these  newly 
discovered  volatile  bases,  pyridine,  quinoline,  etc.  It  was  not  until 
1867  that  these  bases  were  more  definitely  studied,  and  the  fact  es- 
tablished that  they  were  not  substituted  ammonias,  but  nitrogenous 
hydrocarbons,  i.  e.,  fundamental  substances  which  could  yield  in- 
numerable derivatives  just  as  did  benzene,  anthracene,  naphthalene, 
etc.  In  1869  the  next  step  was  made  by  Kbrner,  when  he  showed 
that  just  as  naphthalene  is  made  up  of  two  benzene  nuclei,  so  is  qui- 
noline  made  up  of  a  pyridine  and  a  benzene  nucleus,  i.  e.y  benzene  : 
naphthalene  as  pyridine:  quinoline.  Ladenburg,  in  1883,  proved 
the  correctness  of  the  view  by  actually  converting  pyridine  into 
benzene.  In  1869  the  first  "  apo  "  alkaloids  were  made,  i.  e.}  alka- 
loids obtained  from  other  alkaloids  by  the  abstraction  of  one 
molecule  of  water;  thus  apomorphine  and  apocodeine  are  merely 
