VALERIANATE  OF  IRON. 
533 
nearly  insoluble  in  water,  does  not  mix  well  with  cold  water,  but 
repels  it  like  lycopodiuin,  and  boiling  water  gradually  extracts 
the  acid  from  it.    It  dissolves  in  alcohol  and  acids." 
Wittstein,  who  seems  to  have  given  some  attention  to  the  sub- 
ject, says  :  "  The  valerianate  of  peroxide  of  iron  obtained  by 
precipitation  is  a  dark  brick-red  loose  amorphous  powder,  smell- 
ing and  tasting  faintly  of  valerianic  acid ;  it  will  not  mix  with 
cold  water  even  when  rubbed  continuously  with  it,  but  is  instantly 
wetted  by  warm  water,  and  gives  up  a  portion  of  its  acid  to  it." 
The  same  authority  says  :  "  The  affinity  between  the  oxide  of 
iron  and  valerianic  acid  is  so  feeble  that  a  gentle  heat  will  suffice 
to  abstract  the  greater  portion  of  the  acid,  consequently  the  pre- 
cipitation should  only  take  place  in  the  cold.  Even  continued 
treatment  with  cold  water  gradually  abstracts  the  acid,  and  at  the 
same  time  removes  a  little  of  the  oxide  of  iron,  so  that  the  pre- 
cipitate must  not  be  washed  as  long  as  the  water  passing  off  has 
an  acid  reaction." 
The  descriptions  of  the  salt  here  given  agree  pretty  closely 
with  the  preparation  as  met  with  in  commerce,  with  the  excep- 
tion of  the  solubility  in  alcohol.  Although  I  have  examined 
about  a  dozen  specimens  procured  from  various  houses  in  London, 
and  some  in  the  provinces,  I  have  found  none,  with  the  excep- 
tion of  a  specimen  sent  me  by  an  esteemed  member  of  this  Con- 
ference, Mr.  Daniel  Hanbury,  which  would  dissolve  in  any  appre- 
ciable proportion  in  alcohol. 
The  bulk  of  the  samples  examined  consisted  mainly  of  peroxide 
of  iron,  with  small  quantities  of  valerianic  acid  in  the  compound. 
No  two  preparations  were  precisely  alike  in  composition,  owing 
no  doubt  to  the  fact  that  as  prepared  in  the  way  usually  directed, 
and  dried  by  artificial  heat,  the  loss  of  valerianic  acid  was  con- 
siderable. 
The  specimen  sent  me  by  Mr.  Hanbury  was  in  the  form  of  a 
soft  extract,  smelling  very  strongly  of  valerianic  acid,  and  of  a 
transparent  ruby  color, — agreeing,  in  fact,  precisely  with  a  speci- 
men I  had  myself  prepared  some  months  previously,  but  had  not 
been  able,  owing  to  business  engagements,  to  investigate.  It  is 
best,  perhaps,  here  to  say  that  when  following  the  usual  direc- 
tions for  preparing  the  salt,  I  had  invariably  obtained  the  brick- 
red  powder  described  by  Pereira  and  Wittstein. 
