ON  CHRYSOPHANIC  ACID. 
355 
over  a  water-bath  at  100°  C;  the  residue,  composed  of  sulphate 
of  soda  and  glycerin,  is  taken  up  by  alcohol,  which  dissolves 
only  the  latter ;  it  is  then  filtered  and  evaporated  to  dryness, 
when  the  residue  will  be  glycerin.  This  is  again  taken  up  by 
alcohol,  re-evaporated,  and  the  residue  again  weighed,  after 
ascertaining  that  it  possesses  all  the  properties  of  glycerin. 
Water. — Cut  the  soap  into  thin  slices ;  weigh  5  grms.,  and 
dry  them  on  a  stove  at  120°  C. 
COMPOSITION  OF  VARIOUS  KINDS  OF  SOAP. 
Substances  estimated. 
I. 
II. 
III. 
IV. 
Water,  .... 
.  46-12 
24-76 
17-55 
1409 
Soda,  .... 
.  4-98 
7-30 
8-48 
901 
Fatty  acids, 
.  37-99 
64-50 
7J-45 
74-68 
Chloride  of  sodium,  . 
6-30 
3-12 
2-12 
2-00 
Sulphate  of  soda, 
.  0-72 
0-32 
0-40 
0-22 
Fatty  bodies, 
,  1-00 
Glycerin, 
.  2-89 
Total, 
100  00 
100-00 
100  00 
100  00 
\_Chemical  News^  London,  Feh,  4,  1870. 
ON  CHRYSOPHANIC  ACID. 
By  Dr.  Rochleder. 
After  referring  at  some  length  to  the  labors  of  many  chemists, 
as  well  as  those  made  by  himself  on  this  subject  some  years  ago, 
the  author  enters  into  a  discussion  on  the  statements  made  by 
MM.  Graebe  and  Liebermann  respecting  the  composition  of 
chrysophanic  acid,  and  then  says,  that  he  has  taken  the  trouble 
to  prepare  this  acid  in  pure  state  from  rheine,  as  prepared  by 
Dr.  Marquardt,  at  Bonn ;  this  substance  consists  mainly  of 
chrysophanic  acid,  emodine,  and  impurities ;  the  composition  of 
pure  emodine  dried  at  100°  is,  in  100  parts,  C,  65-75;  H,  4-29; 
0,  30*18  ;  formula:  C^oHg^Ojo ;  the  formula  which  Messrs.  Graebe 
and  Liebermann  give  for  chrysophanic  acid,  viz.,  C^^IIgO^,  can- 
not, according  to  the  author  of  this  paper,  be  the  correct  one, 
and  this  the  less  so,  as  no  less  than  six  different  chemists  have 
found  for  the  formulae  of  this  substance,  prepared  from  different 
sources  and    at   various   periods,   the  formula,  ^s>flJ^ii—^ 
