682       Freezing  Jlixtures  with  Carbonic  Anhydride.  {^•>?ov!";i^^''"'" 
Moreover^  the  heart  and  blood  vessels  themselves  take  a  certain  active 
part  in  the  causation  of  the  rise. 
(7)  Both  the  central  and  peripheral  vaso-dilatory  apparatuses  re- 
main wholly  intact. — Med.  Chronicle,  Sptb.,  1888  ;  from  Ejened.  Klin. 
Gaz.,  1888^,  Xos.  25,  26. 
FREEZING  MIXTURES  COXTAIXIXG  SOLID  CARBOXIG 
AXHYDRIDE.^ 
By  L.  Cailletet  and  E.  Colardeau. 
The  temperatures  were  measured  by  means  of  a  thermoelectric 
couple  which  had  been  graduated  against  a  hydrogen  thermometer. 
Compressed  or  porous  solid  carbonic  anhydride  alone,  under  atmo- 
spheric pressure,  gives  a  tempemture  of  about  — 60°  ;  in  a  vacuum 
maintained  by  means  of  a  pump  and  potash  the  temperature  is  — 76°. 
A  mixture  of  ether  and  solid  carbonic  anhydride  has  a  temperature  of 
— 77°  under  ordinary  pressure,  and  — 103°  in  a  vacuum.  This  mix- 
ture solidifies  liquid  carbonic  anhydride. 
When  solid  carbonic  anhydride  is  added  to  ether,  it  at  first  disap- 
pears rapidly,  not  owing  to  volatilization,  but  because  it  dissolves  in 
the  ether.  The  ether  remains  transparent,  but  after  some  time  bubbles 
of  gaseous  carbonic  anhydride  are  given  off.  If  further  quantities  of 
the  anhydride  are  added,  the  liquid  becomes  saturated,  and  loses  its 
transparency.  The  temperature  gradually  falls  until  it  attains  a 
minimum  exactly  at  the  point  of  saturation.  Any  further  addition  of 
the  anhydride  causes  no  further  reduction  of  temperature,  but  the 
liquid  becomes  more  and  more  turbid.  It  is  evident  that  the  effect  of 
the  ether  is  due  to  its  solvent  action  on  the  carbonic  anhydride.  Other 
solvents  producing  low  temperature  with  the  anhydride  are  methyl 
chloride,  — 82°  ;  sulphurous  anhydride,  — 82°  ;  amyl  acetate,  — 78°  ; 
phosphorus  trichloride,  — 76°  ;  alcohol,  — 72°  ;  and  ethylene  chloride, 
— 60°.  The  temperature  of  mixtures  of  carbonic  anhydride  with 
methyl  chloride  or  sulphurous  anhydride  iu  a  vacuum  is  so  low  that 
the  solvent  solidifies,  and  the  temperature  of  the  mass  remains  con- 
stant from  this  point.  AYith  methyl  chloride  the  temperature  obtained 
is  — 106°.  A  mixture  of  carbonic  anhydride  and  chloroform  becomes 
solid  under  ordinary  pressure,  and  has  a  temperature  of  — 77°. 
^  Campt.  Rend.,  cvi.,  1631—1634 ;  reprinted  from  Jour.  Chem.  Soc,  October,  p. 
1025. 
