312  Epinephrin  and  its  Compounds.  {Amju°^9Polarm' 
The  crystalline  precipitate  is  immediately  filtered  and  subjected 
to  a  prolonged  washing  with  water  and  to  a  shorter  washing  with 
absolute  alcohol  and  ether,  and  it  is  then  dried  over  sulphuric  acid. 
When  dry,  the  material,  which  is  already  almost  snowy-white,  was 
found  to  weigh  23*79  grammes. 
Owing  to  the  very  great  solvent  power  of  trichloracetic  acid,  even 
in  absolute  alcohol,  for  earthy  phosphates  and  other  salts,  the  pre- 
cipitate just  described  is  considerably  contaminated  with  mineral 
constituents  (phosphates),  even  to  the  extent  of  10  or  12  per  cent. ; 
but  even  so,  the  material  seems  pure  enough  in  other  respects  for  all 
local  therapeutic  applications  in  the  strength  of  solution  usually 
employed.  As  regards  these  mineral  constituents  and  other  pos- 
sible impurities  contained  in  the  crystalline  precipitate,  it  will 
presently  be  shown  how  easily  these  may  be  removed. 
But  in  spite  of  the  large  yield  of  the  active  principle  obtained  by 
this  process,  it  will  be  found  to  be  of  great  advantage  to  repeat  the 
extractions  one  or  more  times  with  the  following  modification : 
To  the  once-exhausted  glands,  5  or  6  litres,  not  of  absolute,  but 
of  60  or  70  per  cent,  alcohol,  containing  30  or  40  grammes  of  tri- 
chloracetic acid,  are  added  and  the  whole  process  of  filtration, 
evaporation  and  precipitation  proceeds  as  before.  During  the 
evaporation  of  these  later  extractions  care  must  be  taken  that  they 
maintain  an  acid  reaction,  as  otherwise  great  injury  will  be  done  to 
the  active  principle,  and  one  runs  the  risk  of  obtaining  a  final  prod- 
uct consisting  largely  of  phosphates,  the  active  principle  remaining 
in  solution  in  a  partially  oxidized  or  otherwise  altered  form. 
From  the  weight  of  glands  (11*13  kilogrammes)  used  in  the  above 
instance  I  obtained  from  the  second  extract  8-57  grammes;  from  the 
third  extract  3  grammes.  It  will  thus  be  seen  that  the  sum  total  of 
crystalline,  though  somewhat  impure,  material  obtained  from  11*13 
kilogrammes  of  trimmed  glands  amounted  to  35*36  grammes. 
When  we  take  into  consideration  that  the  glandular  material  is  not 
yet  completely  exhausted,  that  with  better  appliances  for  filtration 
a  still  better  yield  could  be  obtained,  it  is  apparent  that  the  amount 
of  the  active  principle  contained  in  beeves'  glands  has  been  hitherto 
underrated,  and  that  it  may  safely  be  assumed*  as  constituting  at 
least  0*3  per  cent,  of  the  moist  gland.  It  need  only  be  added  that 
the  cheaper  methyl-alcohol  will  no  doubt  serve  equally  well  for 
extraction.    I  have,  however,  as  yet  found  no  other  acid  to  equal 
