Ams5t'i87™'}  Preparation  of  Extracts  without  Heat.  \tf 
ON  A  NEW  PROCESS  FOR  THE  PREPARATION  OF 
EXTRACTS  WITHOUT  HEAT. 
By  Professor  Alphonse  Herrera. 
Since  the  progress  of  organic  chemistry  has  made  us  acquainted  with 
many  proximate  principles  of  plants  and  their  various  properties,  the 
processes  for  most  medicinal  preparations  have  been  considerably  im- 
proved, and  diverse  apparatus  and  methods  have  been  designed  with  the 
view  of  obtaining  them  in  a  more  energetic  form  and  of  preventing  the 
alteration  of  the  proximate  principles,  as  well  as  to  secure  greater 
economy  and  a  more  convenient  form  for  their  administration.  Of  all 
the  medicinal  preparations  none  have  attracted  more  the  attention  of  the 
pharmacists  than  the  extracts,  which  offer  the  advantage  of  being  con- 
veniently administered,  and,  if  well  prepared,  of  representing  in  a  small 
bulk  the  properties  of  the  drugs.  By  the  action  of  heat  and  air  the 
organic  principles  are  generally  more  or  less  altered,  and  hence  in  the 
ordinary  way  of  preparing  extracts,  the  active  ingredients  are  more  or 
less  modified,  or  if  volatile,  evaporated,  and  the  preparations  do  not 
fully  represent  the  drug.  To  obviate  this  difficulty,  it  has  been  pro- 
posed to  evaporate  the  liquids  at  a  rather  low  temperature,  and  if  pos- 
sible excluded  from  contact  with  the  air,  and  with  these  objects  in 
view,  ingenious  apparatus  and  contrivances  have  been  adopted  :  like 
evaporating  in  many  capsules  heated  by  steam,  as  in  the  process  of  Henry ; 
or  keeping  the  liquid  continually  in  motion  to  promote  the  evaporation, 
as  in  the  process  of  Bernard  ;  or  effecting  the  concentration  in  vacuo 
by  means  of  special  apparatus,  constructed  by  Laurent,  Granval,  Berry 
and  others. 
I  do  not  propose  to  discuss  the  advantages  or  disadvantages  of  the 
different  methods  proposed,  for  they  are  well  known.  It  merely 
remains  to  state  that  the  best  results  have  been  obtained  by  evaporation 
in  vacuo,  in  which  process  the  exclusion  of  air  and  the  low  heat  prevent 
any  great  alteration  of  the  soluble  principles  ;  but  the  high  price  of 
such  an  apparatus  is  a  great  obstacle  to  its  general  use. 
For  many  years,  sodium  chloride  and  ice  have  been  employed  in 
Europe  with  the  object  of  utilizing  the  property  of  water  when  freezing 
to  separate  the  salts  which  are  contained  in  solution.  In  1862  Robinet 
presented  to  the  Paris  Academy  of  Medicine  a  memoir,  in  which  he 
demonstrated  the  application  of  this  behavior  in  the  analysis  of  waters. 
Afterwards  Mr.  Ossian  Henry  has  applied  it  to  the  concentration  of 
