AN  AUTOMATIC  VACUUM  APPARATUS. 
129 
AN  AUTOMATIC  VACUUM  APPAKATUS. 
By  N.  Gray  Bartlett. 
It  is  highly  probable  that,  had  the  framers  of  our  national 
Pharmacopoeia  foreseen  the  enhanced  value  of  alcohol,  many  of 
the  officinal  formulas  would  have  been  greatly  modified,  to  insure 
a  more  economical  use  of  this  important  menstruum ;  and  in  no 
instance  would  this  modification  be  more  apparent  than  in  the 
mode  and  temperature  prescribed  for  the  evaporation  of  spiritu- 
ous liquids. 
These  defects  have  been  the  means  of  defeating,  to  some  ex- 
tent, the  objects  of  the  Pharmacopoeia;  the  pharmaceutist,  if  he 
relinquish  the  preparation  of  those  articles  involving  a  great 
waste  of  alcohol,  and  purchase  them  of  the  wholesale  manufac- 
turer, neglects  one  of  the  most  important  duties  of  his  avocation, 
while,  if  he  ignore  the  authoritative  directions  in  this  respect,  he 
establishes  a  most  reprehensible  precedent,  an  act  not  excusable 
by  the  plausible  plea  that  equally  efficient  preparations  are  se- 
cured by  this  alternative. 
The  presumption  is  not  unfounded  ;  indeed,  it  is  the  conviction 
of  the  writer  that,  as  a  general  rule,  spirituous  solutions  of  or- 
ganic matter  evaporated  at  120°,  140°,  or  160°,  and,  necessarily 
long  exposed  to  the  combined  influences  of  heat  and  air,  suffer 
greater  injury  than  would  ensue  from  the  use  of  the  water-bath 
still,  the  difference  of  temperature  being  more  than  compensated 
for  by  the  exclusion  of  the  atmosphere  and  the  rapid  concentra- 
tion of  the  liquid. 
Vacuum  evaporation,  which  effectually  precludes  all  danger  of 
oxidation  and  of  injury  by  an  excessive  degree  of  heat,  is  gene- 
rally acknowledged  to  furnish  products  far  superior  to  those 
otherwise  obtained. 
To  secure  this  desideratum  by  the  apparatus  at  present  in  use 
is  attended,  in  addition  to  the  large  original  outlay,  with  constant 
expense ;  as  a  consequence  it  is  available  only  to  the  extensive 
manufacturer. 
It  is  the  object  of  this  paper  to  call  attention  to  a  new  form  of 
vacuum  apparatus,  one  which,  it  is  believed,  will  recommend  it^ 
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