454 
Precipitates  in  Fluid  Extracts. 
Am.  Jour.  Pharm. 
Sept.,  1884. 
proportion  is  in  favor  of  the  iron,  the  water  has  less  power  to  free 
itself  and  climb  away. 
Can  it  be,  then,  that  capillary  or  surface  attraction  has  the  power  to 
dissociate  a  solution  ?  If  so,  it  seems  to  us  that  this  fact  must  have 
been  overlooked  in  many  instances  where  its  consideration  was  a  neces- 
sity to  accuracy  in  results. 
In  looking  at  the  phenomenon  as  presented  in  the  foregoing  portion 
of  our  paper,  it  will  be  seen  that  we  may  sum  up  the  matter  as  follows : 
1st.  The  bibulous  paper  absorbs  and  carries  to  a  certain  height  the 
liquid  about  as  it  exists  in  the  vessel. 
2d.  At  a  point  above  the  surface  of  the  liquid,  determined  by  the 
texture  of  the  paper  and  the  concentration  of  the  solution,  the  iron  salt 
ceases  to  pass  upward1  as  rapidly  as  the  water  or  other  substances  held 
in  solution  by  the  water. 
3d.  Then  the  liquids  separate,  and  the  colorless  liquid  is  actually 
-A 
-A- 
A- 
-A- 
ML* 
a 
A,  colorless  liquid.    B,  ferric  sulphate.    C,  surface  of  liquid.    The  left  hand  figure  is 
officinal  solution  of  tersulphate  of  iron. 
drawn  (or  thrust)  through  the  solution  of  iron  without  carrying  a  trace 
of  ferric  sulphate  beyond  the  line  of  division. 
1  We  use  the  term  upward  to  correspond  with  this  line  of  experiments. 
The  same  phenomenon  is  presented  when  the  paper  is  horizontal  or  inclined, 
if  capillary  attraction  only  carries  the  liquid  outward. 
