409 
The  replacement  of  the  amino  group  by  an  hydroxyl  group 
changes  the  character  of  the  compound  in  the  case  of  Orsudan  as  it 
does  in  Atoxyl.  It  is  extremely  toxic  and  showed  only  a  very  shg'ht 
action  on  the  parasites,  and  only  when  injected  in  so  large  doses  as 
O'OS  gm.,  m  which  case  it  killed  the  animal  in  a  few  hours. 
2.  Di-sodium-4-di-methyl-amino  2-methyl-azo-benzene  4-arsenate. 
was  found  to  have  a  slight  effect  on  trypanosomes.  Thej^  decreased 
m  number,  but  the  rats  usually  died  within  a  few  days.  When 
compared  with  the  corresponding  Atoxyl  derivative  No.  5,  p.  401,  it  is 
seen  that  although  the  combining  ammo  group  is  saturated  through 
diazotising,  in  this  case  the  CHg  group  most  probably  gets  oxidised  to 
a  COOH  group,  through  which  a  combination  with  the  proteids  takes 
place. 
3.  Sodium  di-(3 -methyl  4-amino-phenyl)  arsenate 
CH 
o 
It 
A  S 
N  H2 
ONa 
and  Sodium  di-(3 -methyl  4-acetyl-amino-phenyl)  arsenate 
CH3 
H3C0CHN-<^\  - /  Nnhcoch, 
ONa  X—/ 
had,  in  the  same  way  as  the  corresponding  Atoxyl  derivative,  on 
injection,  no  effect  on  rats  infected  with  T .  eqiiiperdum. 
COLOURING  MATTERS 
Since  Ehrlich  and  Shiga’s  discovery  that  trypanred  has  a 
pronounced  trypanocidal  action,  numerous  colouring  matters  of 
different  chemical  constitution  have  been  tried  in  experimental 
Trypanosomiasis  with  a  more  or  less  therapeutical  success. 
