Am.  Tour.  Pharm. 
May,  19 1 9. 
Preparation  of  Arsphenamine. 
307 
Magnesium  mixture,  used  as  described,  showed  no  inorganic 
arsenic. 
Mayer's  reagent  for  alkaloids,  gave  the  characteristic  test. 
Mercuric  chloride  showed  the  precipitate  described. 
Carbon  dioxide  precipitates  the  base  from  its  alkaline  solution, 
as  is  very  characteristic  for  salvarsan,  showing  the  presence  of  a 
very  weakly  acid  substance. 
Physical  Properties. — The  substance  as  soon  as  it  is  moistened 
with  water  becomes  brownish  yellow  and  dissolves  in  5  parts  of 
water  to  form  a  gel  or  gelatinous  solution  depending  on  the  tempera- 
ture. It  is  readily  soluble  in  warm  or  hot  water,  slightly  soluble  in 
methyl  alcohol,  scarcely  soluble  in  ethyl  alcohol,  insoluble  in  ether  or 
benzene. 
Melting  Point. — It  does  not  melt  slowly  when  heated,  but 
gradually  darkens,  beginning  at  160  0  C;  when  at  about  1800  C.  it 
begins  to  char.  Ehrlich  and  Bertheim  State  that  their  product  de- 
composes, depending  on  the  speed  of  heating  at  about  185-195 0  C. 
with  charring. 
Toxicity. — In  general  its  other  properties  seem  to  be  that  of 
salvarsan  in  every  respect.  When  tested  by  injection  into  rats  ac- 
cording to  the  rules  and  standards  recommended  by  the  U.  S.  Public 
Health  Service  and  adopted  by  the  Federal  Trade  Commission,15  it 
seems  to  have  a  relatively  low  grade  of  toxicity. 
IV.  General  Discussion. — Our  work  on  arsphenamine  seems 
to  show  that  the  dihydrochloride,  when  pure  and  possessing  only  one 
or  two  molecules  of  water,  is  practically  colorless.  Samples  of  this 
colorless  form  can  be  shown  and  are  easily  prepared.  Impure 
arsphenamine  is  tinted  more  or  less,  depending  on  the  impurity  and 
also  on  the  physical  form  of  the  solid  substance.  Of  the  three  com- 
mercial preparations  made  in  America  no  two  are  alike  in  color. 
The  Canadian  Diarsenol  is  very  yellow,  the  Metz  preparation  less 
yellow  with  a  tint  of  green,  while  the  Arsenobenzol  has  a  light 
yellow  tint. 
The  amount  of  yellow  tint  may  be  due  to  the  sulphur  content,  as 
our  gray  substances  have  about  one  half  to  one  fourth  the  amount 
of  sulphur  that  is  present  in  the  ordinary  yellow  material. 
The  analyses  of  arsphenamine  indicate  that  the  amount  of  colored 
impurity  in  most  preparations  must  be  negligibly  small,  at  most  1 
per  cent,  or  less.    The  toxicological  studies  also  show  that  the 
16  Public  Health  Reports,  33,  540,  1918. 
