ON  THE  COLOR  OF  WATER. 
509 
volatile  body.  The  liquid  in  the  still  was  precipitated  with  ace- 
tate of  lead,  and  the  precipitate  treated  with  acetic  acid ;  the 
two  lead  compounds  thus  obtained  contain  new  humic  acids, 
probably  derived  from  the  tannin,  and  have  the  composition 
4PbO,  and  3PbO,  G,J1.,,0^,. 
The  air  dry  bark  yielded  8-7  pr.  ct.,  the  anhydrous  bark  10  per 
cent,  ashes  which  consisted  of  KG  27-23,  NaO  -67,  NaCl  -16, 
CaO  25  32,  MgO  5-62,  AUG,  1  20,  Fe^Gg  -95,  SG3  -71,  PGg 
3.86,  SiGg  6.31,  CG2  27.97.^^ 
It  is  evident  that  the  composition  of  this  bark  does  not  coin- 
cide with  its  high  reputation. — ( Wittsteins  V.  Schr.  x.  321-342.) 
ON  THE  COLOR  OF  WATER. 
By  Professor  Wittstein. 
Pure  water,  according  to  Bunsen,  has  a  blue  color,  while  ad- 
ditions of  other  bodies,  or  the  reflection  from  a  colored  bottom, 
cause  the  color  to  appear  differently.  This  can  be  verified  by 
looking  at  white  objects  upon  a  white  surface  through  a  column 
of  water,  2  metres  in  height,  or  by  allowing  the  sunlight  to  shine 
upon  these  objects  after  it  has  passed  through  such  a  column  of 
water. — [Ann,  der  Chem.  und  Ph.  Ixxii.  44.) 
Dr.  G.  C.  Wittstein  discusses  the  causes  of  the  different  colors 
of  natural  water,  and  cites  analyses  performed  by  himself  and 
others,  of  the  water  of  several  rivers  in  Bavaria,  from  which  he 
arrives  at  the  following  conclusions : 
1.  Pure  water  is  not  colorless,  but  blue. 
2.  Mineral  substances  dissolved  in  natural  waters,  do  not  alter 
their  color. 
3.  The  various  colors  of  natural  waters  are  due  to  dissolved 
organic  matter. 
4.  This  organic  matter  is  retained  in  solution  by  the  aid  of 
alkali,  is  in  mass  deep  brownish  black,  in  diluted  solutions  yel- 
lowish to  brown  and  belongs  to  the  humic  acids. 
5.  The  quantity  of  the  organic  matter  in  solution  depends 
solely  on  the  quantity  of  the  alkali. 
6.  The  less  organic  matter  is  dissolved  in  the  water,  the  less 
