Am.  Tour.  Pharm. 
May,  1919. 
Preparation  of  Arsphenamine . 
301 
The  reference  or  work  chiefly  if  not  wholly  relied  upon  for  this 
assumption  is  that  of  Gaebel.6  Myer7  and  DuMez  quote  him  also  in 
support  of  the  arsenic  regulations  of  the  drug.  While  other  authors 
make  arsenic  estimations,  Gaebel  is  the  only  author  mentioned  or 
that  I  can  find,  beside  Ehrlich  and  Bertheim,  who  has  made  any 
experiments  as  to  the  solvent  and  its  amount  in  the  dry  substance. 
Gaebel  passed  hydrogen  gas,  purified,  over  0.07966  Gm.  salvar- 
san,  contained  in  a  glass-vessel  called  "Ente"  (meaning  goose- 
shaped),  heated  in  an  oven  at  105°  C. ;  the  vapor  coming  off  was 
tested  only  for  hydrochloric  acid  with  silver  nitrate  solutions.  He 
weighed  the  "  Ente  "  and  noted  the  loss  of  weight.  After  6  hrs.  its 
weight  became  constant  and  the  loss  corresponded  to  7.2  per  cent. 
The  theoretical  loss  for  2  molecules  of  water  would  be  7.6  per  cent. 
This  one  estimation  apparently  satisfied  him  for  he  records  no 
duplicate  estimation,  and  called  the  solvent  thus  lost  water,  appar- 
ently taking  no  account  of  the  fact  that  arsphenamine  was  actually 
precipitated  from  methyl  alcohol  (undoubtedly  anhydrous  so  as  to 
mix  with  the  ether)  with  non-aqueous  ether.  That  Gaebel  simply 
assumed  it  to  be  water,  not  knowing  the  method  of  Ehrlich  and 
Bertheim  used  is  indicated  also  by  the  fact  that  he  published  a  year 
before  Ehrlich  and  Bertheim  published  their  method. 
Against  the  statement  that  the  solvent  in  the  solid  arsphenamine 
is  water,  are  the  words  and  experiments  of  Ehrlich  and  Bertheim.8 
They  tested  one  preparation  made  with  methyl  alcohol  and  ether,  in 
the  same  way  all  their  preparations  are  supposed  to  be  made,  after 
drying  the  substance  at  65°  C.  in  a  current  of  carbon  dioxide.  This 
temperature  is  about  the  boiling  point  of  methyl  alcohol.  On  dis- 
solving this  dried  preparation  in  water  and  distilling  over  any  volatile 
solvents  they  found  methyl  alcohol  in  appreciable  quantities.  They 
concluded  upon  this  and  other  reliable  analyses  that  it  contained  one 
molecule  of  methyl  alcohol  for  every  molecule  of  the  arsphenamine. 
In  view  of  these  facts,  it  seems  fairly  certain  that  arsphenamine 
made  according  to  the  original  directions  must  contain  methyl, 
alcohol,  unless,  of  course,  it  is  removed  by  drying  under  more  favor- 
able conditions  than  Ehrlich  and  Bertheim  used.  The  evidence  in 
the  literature  gives  one  the  strong  impression  that  for  commercial 
reasons  its  methyl  alcohol  content  has  been  kept  secret.    The  ob- 
6  Apoth.  Ztg.,  26.  215-216,  1911. 
'Public  Health  Reports,  33,  1004,  1918. 
-     %Bcr.,  45.  756,  1912. 
