Am'May'•l|,95a^m•}       The  Chemistry  of  Ipecacuanha.  257 
The  other  alkaloid — cephaeline — is  crystallizable,  less  soluble  in 
ether  than  emetine,  but  freely  soluble  in  alcohol  or  chloroform, 
much  more  soluble  than  emetine  in  hot  petroleum  spirit,  and  readily 
soluble  in  solutions  of  caustic  alkali. 
By  these  characters  the  difference  between  the  two  alkaloids  is 
very  distinctly  marked.  There  are  also  differences  in  their  melting 
points — emetine  melting  at  68°  C,  cephaeline  at  1020  C. — and  in 
their  percentage  composition,  as  is  shown  by  the  following  com- 
parison : 
Emetine.  Cephaeline. 
Carbon  72*01  71*28 
Hydrogen   8*86  8*69 
Nitrogen  :   5*75  6*24 
Oxygen  13*38  13*79 
I  OCT  TOO' 
These  figures  give  as  their  most  simple  expression  the  following 
formulae  : 
Emetine.  Cephaeline. 
C15H22N02  =  248  C14H20NO2  =  234 
Analysis  of  the  neutral  hydrochloride  salts  has  shown  that  the 
quantities  corresponding  to  these  formulae  are  respectively  equiva- 
lent to  one  molecule  of  hydrochloric  acid. 
The  very  marked  peculiarity,  common  to  both  alkaloids,  of  form- 
ing crystalline  salts  more  readily  in  the  presence  of  excess  of  acid 
than  when  neutral  solutions  are  slowly  evaporated,  led  at  first  to 
the  erroneous  conclusion  that  neutral  cephaeline  salts  were  uncrys- 
tallizable  and  that  the  crystallizable  salts  of  both  emetine  and 
cephaeline  were  acid  salts.  It  has  since  been  ascertained  that 
cephaeline  hydrochloride  can  be  obtained  in  well-defined  prismatic 
crystals  when  a  slightly  acidified  solution  is  slowly  evaporated,  and 
that  this  salt  contains  equal  molecular  proportions  of  alkaloid  and 
acid. 
In  the  case  of  emetine  the  influence  of  an  excess  of  acid  in  deter- 
mining the  formation  of  a  crystalline  salt  is  still  more  marked.  On 
adding  a  drop  of  moderately  strong  hydrochloric  acid  to  a  particle 
of  emetine,  a  mass  of  acicular  crystals  is  at  once  formed. 
Both  emetine  and  cephaeline  are  very  sensitive  to  the  influence  of 
light.  Though  perfectly  colorless  when  pure  and  in  a  free  state, 
they  rapidly  acquire  a  yellow  color  when  exposed  to  sunlight. 
