Ferric  Ethylate.  323 
FERRIC  ETHYLATE  AND  COLLOIDAL  FERRIC 
HYDRATE. 
By  E.  Grimaux. 
When  1  mol.  of  ferric  chloride  in  alcoholic  solution  is  mixed  with 
6  mols.  of  sodium  ethylate,  sodium  chloride  is  precipitated,  and  a  deep 
red-brown  limpid  liquid  is  obtained,  which  is  free  from  chlorine,  but 
contains  all  the  iron  in  solution  as  ferric  ethylate.  The  alcohol  can 
be  distilled  off,  and  the  ferric  ethylate  is  left  as  a  black  pasty  mass, 
soluble  in  absolute  alcohol,  benzene,  chloroform,  ether,  petroleum,  and 
methyl  alcohol.  If,  however,  this  residue  is  heated  in  a  vacuum  so  as 
to  expel  the  last  traces  of  the  solvent,  the  small  quantity  of  water  pres- 
ent almost  completely  decomposes  the  ethylate,  and  ferric  hydroxide 
separates  out.  If  the  operations  of  filtration,  etc.,  have  been  conducted 
in  dry  air,  the  ethylate  is  not  completely  decomposed.  An  alcoholic 
solution  of  ferric  ethylate  is  not  precipitated  by  a  current  of  dry 
ammonia,  but  with  dry  carbonic  anhydride  it  yields  a  brown  precipi- 
tate. Dry  hydrogen  sulphide  reduces  it  to  a  ferrous  salt,  and  potas- 
sium ferrocyanide  precipitates  ferric  hydroxide. 
The  action  of  water  varies  with  the  proportion  in  which  it  is  present. 
If  the  alcoholic  solution  is  exposed  to  a  moist  atmosphere,  or  is  mixed 
with  a  small  quantity  of  water,  ferric  hydrate  is  deposited  as  a  jelly. 
If,  however,  the  alcoholic  solution  of  ferric  ethylate  is  poured  into  an 
excess  of  water,  limpid  liquids  are  obtained  which  have  the  properties 
of  the  solutions  of  colloidal  ferric  hydroxide  described  by  Graham. 
They  coagulate  spontaneously  after  some  time,  and  are  coagulated  by 
addition  of  various  substances,  such  as  carbonic  anhydride,  sulphuric 
acid,  tartaric  acid,  potassium  chloride,  sodium  chloride,  river  water,  etc. 
Acetic,  nitric,  and  hydrochloric  acids  and  ammonia  have  no  effect. 
Hydrogen  sulphide  produces  a  black  precipitate.  The  time  which 
elapses  before  coagulation  takes  place  increases  with  the  dilution  of  the 
solution,  and  is  diminished  by  an  increase  of  temperature.  A  higher 
temperature  is  required  to  produce  coagulation  the  greater  the  amount 
of  water  present,  and  a  solution  of  1  vol.  ferric  ethylate  solution  in  J  5 
vols,  of  water  is  not  coagulated  even  after  four  hours'  ebullition. 
The  coagulated  ferric  hydroxide  forms  a  thick  jelly,  which  always 
fills  the  vessel  even  if  the  solution  is  dilute.  At  first  it  is  transparent, 
but  it  gradually  contracts  with  elimination  of  water.  The  coagula- 
tion of  the  ferric  hydroxide  varies  with  the  conditions  in  the  same 
way  as  the  coagulation  of  blood,  a  fact  which  indicates  that  inorganic 
Am.  Jour.  Pharm. ) 
June,  1884.  / 
