264 
DRYING  OF  OILS  BY  METALLIC  SALTS. 
the  vessels  in  which  the  experiment  is  performed,  never,  however, 
exceeding  half  a  degree  Centigrade.  It  is  greater  when  the  com- 
parison is  made  between  water  and  wet  sand  placed  in  two  similar 
metallic  vessels,  than  when  they,  are  placed  in  porcelain  or  glass 
vessels  ;  in  the  latter  case  it  seldom  exceeds  0-1°  to  0-2°. 
The  author  concludes  by  remarking,  that  the  foregoing  result 
tends  to  confirm  an  opinion  expressed  some  time  since  by  Pro- 
fessor De  la  Rive,  in  a  letter  to  M.  Arago,  published  in  the 
Oomptes  Rendus  de  VAcademie  des  Sciences  for  October,  1851. 
In  this  letter,  M.  De  la  Rive  attributes  the  sudden  appearance  of 
vast  glaciers  in  divers  part  of  Europe  to  a  temporary  refrigeration 
produced  at  the  period  of  the  elevation  of  the  most  recent  Euro- 
pean strata,  by  the  evaporation  of  the  water  with  which  they 
were  previously  covered.  If,  as  the  author's  experiments  tend  to 
show,  evaporation  takes  place  more  rapidly  from  water  mixed 
with  sand,  earth,  or  any  similar  substance  than  from  a  surface 
of  clear  water,  it  becomes  natural  to  conclude,  that  the  cold  pro- 
duced by  evaporation  from  the  recently-elevated  and  still  humid 
strata,  must  have  been  greater  than  that  resulting  from  the 
evaporation  of  the  sea  or  fresh  water  lake  which  covered  them 
previously  to  a  great  depth. — Bibliotheque  Universelle,  April, 
1853.,  from  Frank.  Inst.  Jour,  and  Repert.  of  Pat.  Inv. 
THE  ACCELERATION  OF  THE  DRYING  OF  OILS  BY  METALLIC 
SALTS. 
By  Barruel  and  Jean. 
According  to  the  researches  of  Berthollet  and  Saussure,  the 
drying  oils  do  not  absorb  considerably,  for  a  long  time,  oxygen 
from  the  air ;  but  suddenly  follows,  after  this  inactivity,  a  rapid 
and  almost  violent  reaction,  which  may  be  recognised  by  a  con- 
siderable evolution  of  carbonic  acid  without  a  noticeable  forma- 
tion of  water,  and  at  the  same  time  the  oil  dries  with  an  increase 
of  weight. 
First  of  all,  we  found  that  an  oil  which  contained  no  drying 
oil  or  any  other  drying  agent,  began  after  five  or  six  days  to 
evolve  carbonic  acid.  In  contrary  instances,  the  evolution  of 
carbonic  acid  commenced  after  eight  or  ten  hours'  contact  with 
the  air. 
