t 
374  ACTIVE  PRINCIPLE  OF  SENNA.  - 
not  decompose  by  heat  or  exposure  to  the  sun  or  air,  as  is  the 
case  with  india-rubber.  It  is  therefore  better  adapted  than  that 
substance  for  hot  climates.  To  the  chemist,  engineer,  and  manu- 
facturer, linoleum  offers  quite  a  new  substance  for  experiment, 
and  no  doubt,  as  it  becomes  better  known,  the  various  uses  to 
which  it  may  be  applied  will  be  more  fully  developed  and  appre- 
ciated. The  patentees,  we  understand,  are  prepared  to  grant 
licenses  for  the  manufacture  of  some  of  its  applications,  such  as 
varnishes,  cements,  and  the  hard  compounds  above  mentioned. 
Important  results  may  therefore  follow  the  introduction  of  this 
new  and  valuable  substance." — Druggists  Circular ,  June,  1866, 
from  Mechanics'  Magazine. 
ACTIVE  PRINCIPLE  OF  SENNA. 
Prof.  Dragendorff  and  Mr.  Kubly,  of  Dorpat,  have  succeeded 
in  separating  from  senna  leaves  the  true  active  purgative  princi- 
ple, an  acid  to  which  they  have  applied  the  name  of  cathartic 
acid,  formerly  employed  for  an  impure  substance  to  which  the 
active  properties  were  ascribed.  This  acid  principle  is  insoluble 
in  water,  strong  alcohol,  and  ether,  but  enters  into  the  watery 
infusion  combined  with  alkaline  and  earthy  bases.  Acids,  with 
the  exception  of  tannin,  precipitate  it  from  its  solutions  in  dilute 
alcohol.  The  principle  is  obtained  in  an  impure  form  by  treat- 
ing the  syrupy  extract,  obtained  in  vacuo  from  a  strong  watery 
infusion,  with  renewed  portions  of  absolute  alcohol,  rejecting  the 
first  precipitate,  but  collecting  the  subsequent  ones,  which  are 
then  purified  by  repeated  solution  in  water  and  reprecipitation 
by  means  of  absolute  alcohol.  It  is  finally  purified  by  dialysing 
it  with  moderately  strong  muriatic  acid  on  parchment  paper, 
cathartic  acid  possessing  strongly  colloidal  properties.  It  con- 
tains both  nitrogen  and  sulphur,  and  is  a  glucoside,  since  treat- 
ment with  acids  in  the  heat,  caused  splitting  into  another  (ca- 
thartogenic)  acid  and  sugar.  Alkalies,  in  the  heat,  likewise  act 
destructively. 
The  ammonia  salt  of  cathartic  acid  gives  a  brownish,  flocculent 
precipitate  with  salts  of  silver,  and  a  similar  one  with  protochlo- 
ride  of  tin  and  chloride  of  mercury ;  sulphate  of  copper  and  ace- 
