622 
The  Organo-metallic  Bodies. 
(Am.  Jour.  Pharm. 
X     Sept.,  1921. 
obtained  a  liquid  fuming  in  the  air  and  capable  of  spontaneous  com- 
bustion. The  nature  of  this  long  remained  unknown,  and  it  was 
merely  designated  as  "Cadet's  Fuming  Liquor."  A  radicle  termed 
"kakodyl"  As  (CH3)2,  is  the  basis  of  the  principal  ingredients 
in  the  mixture,  and  in  1842  Bunsen  by  a  series  of  most  interesting 
and  wonderful  researches,  elucidated  the  chemistry  of  the  subject 
and  showed  that  the  kakodyl  radicle  can  form  a  large  number  of 
compounds,  most  of  which  are  highly  poisonous.  One  striking  ex- 
ception to  this  quality  was  noted  in  the  case  of  kakodylic  acid, 
HAs  (CH3)  2O2,  the  toxicity  of  which  was  found  to  be  much 
less  than  the  content  of  As  would  indicate.  The  investigation  of 
such  compounds  involves  much  risk,  and  Bunsen  lost  an  eye  in  con- 
sequence of  the  explosion  of  a  tube  in  which  he  was  distilling  one 
of  the  compounds.  Kakodylic  acid  was  introduced  in  medical  use, 
but  has  not  found  any  important  applications,  and  all  these  arsen- 
icals  have  given  way  to  the  benzene  derivatives  of  which  arsphena- 
min  is  the  best  known. 
The  question  of  susceptibility  to  ionization  is  one  which  must 
be  taken  into  account  in  judging  of  the  physiologic  effect  of  any 
substance,  and  in  the  case  of  poisonous  metal,  the  position  of  it  in 
the  ion  will  also  determine  largely  its  effects.  The  contrast  between 
the  cyanides  and  the  ferrocyanides  exemplifies  this  fact. 
The  chemistry  of  the  organic  compounds  of  arsenic  and  anti- 
mony has  been  extensively  treated  by  Gilbert  T.  Morgan  in  a  work 
issued  a  few  years  ago  and  a  glance  at  this  will  show  the  extent  of 
the  researches  along  this  line  and  the  variety  and  complexity  of  the 
compounds  already  known.  It  is  well  known  that  the  original  name 
of  arsphenamin,  "606,"  was  provisionally  given  because  it  was  the 
606th.  derivative  that  was  prepared  in  the  effort  to  find  an  arsenical 
that  should  have  a  much  higher  germicidal  action  than  general  tox- 
icity, so  as  to  permit  it  to  be  used  in  rather  large  doses  in  the  anni- 
hilation of  the  specific  germ  of  syphilis.  The  investigations  along 
this  line  have  continued  and  today  derivatives  analogous  to  ars- 
phenamin have  been  produced  in  great  number,  among  which  are 
some  that  appear  to  be  better  adapted  to  therapeutic  use  than  the 
original  compound. 
The  analogy  between  arsenic,  antimony,  nitrogen  and  phos- 
phorus renders  it  possible  to  obtain  from  the  former  two  compounds 
of  the  same  type  as  ammonia  and  phosphin.    These,  as  might  be 
