116 
ON  THE  PRESERVATION  OP  FLUID  EXTRACTS. 
ture  allowed  to  absorb  a  gas  such  as  air,  and  afterwards  heated 
to  about  85  or  90°  F.  evolve  the  gas,  but  alcohol  in  smaller  pro- 
portion than  ether;  the  same  is  the  case  with  alcohoLand  water, 
at  about  160°  F.,  the  air  is  ejected  from  alcohol  in  larger  pro- 
portion than  from  water. 
However,  on  this  very  subject  we  have  scientific  researches  by 
Saussure,  jun.  He  established  the  fact  that,  even  by  a  long  con- 
tinued boiling,  no  liquid  could  be  absolutely  freed  from  the  gas 
it  had  previously  absorbed,  but  liquids  with  higher  boiling  point 
easier  and  more  complete  than  those  boiling  at  a  lower  tempe- 
rature ;  the  difficulty  to  rid  our  pharmaceutical'menstrua  of  at- 
mospheric air  must  therefore  be  greatest  with  ether,  less  with  al- 
cohol, water,  and  I  may  add  syrup.  According  to  Saussure,  100 
volumes  of  the  following  liquids,  freed  of  air  as  much  as  possible, 
are  able  to  absorb  the  following  volumes  of  gases,  viz  ♦ 
Water,  106  C02      6.5   O,  4.2  N 
Alcohol,  186  CO,     16.25  O,  42  N 
Absolute  alcohol,         260  C0.2 
Ether,  217  CO, 
Syrup  containing  25] 
pr.  ct.  sugar,        J  72 
With  regard  to  the  resorbent  quality  of  liquids,  Berzelius  gives 
the  following  general  rules  :  The  capacity  of  liquids  for  the  ab- 
sorption of  gases  increases  in  general  with  the  decrease  of  their 
specific  gravity,  and  with  very  few  exceptions  this  capacity  is 
lessened  by  the  presence  of  a  salt  or  other  body  ;  the  more  solu- 
ble this  is  in  the  liquid,  or  the  more  of  it  is  dissolved  in  a  given 
measure,  the  smaller  is  the  resorbent  power  of  the  liquid,  or  in 
other  words  the  absorbing  capacity  of  solutions  is  lessened  by 
the  increase  of  their  specific  gravity.  The  little  table  above  is  a 
strong  evidence  against  the  practicability  of  the  use  of  alcohol, 
which  absorbs  2  J  times  more  of  oxygen  than  water,  and  probably 
5  times  more  than  an  equal  volume  of  syrup.  Alcohol  therefore 
is  the  very  liquid  that  furnishes  the  principal  conditions  for  the 
convenient  oxidation  of  vegetable  substances,  ready  mobility  and 
sufficient  oxygen.  Only  in  appearance,  the  experience  of  every 
day  life  is  at  variance  with  this  assertion;  for  above  it  was  shown 
that  alcohol  arrests  putrefaction  and  fermentation  merely  by  de- 
stroying vegetable  and  animal  life,  for  the  successful  continuance 
