162 
01?  A  NEW  ALKALI-METAL. 
Plasma,  consisting  of  glycerine  and  starch,  was  proposed  as  a 
medium  for  external  applications,  in  the  place  of  ointments. 
His  experience  of  this  preparation  had  been,  that  it  became 
mouldy  after  being  kept  for  some  U.mQ.— -Trans.  Pharm.  Society, 
Dec.  5,  1860. 
ON  A  NEW  ALKALI-METAL. 
By  mm,  Bunsen  and  Kirchhoff. 
In  a  recent  number  of  the  Philosophical  Magazine  there  is 
given  an  account  of  some  researches  by  MM.  Bunsen  and  Kirch- 
hoff on  the  effect  produced  by  various  metals  on  the  spectrum  of 
a  flame  in  which  their  chlorides  are  volatilised.  That  part  of 
their  investigation  which  is  more  particularly  interesting  con- 
sists of  a  method  of  photochemical  analysis  of  exquisite  delicacy, 
which  the  authors  have  specially  studied  in  relation  to  the  alkali- 
metals. 
These  metals  have  been  employed  in  the  form  of  chlorides, 
which  have  been  purified  with  the  greatest  care.  When  these 
are  introduced  into  a  jet  of  flame  they  volatilise  to  a  greater  or 
less  extent,  and  then  communicate  to  the  flame  the  special 
character  above  alluded  to,  and  which  is  observable  when  the 
spectrum  produced  by  the  flame  is  examined  by  a  sufficient  mag- 
nifying power. 
The  above  named  memoir  is  accompanied  by  a  color  plate 
which  illustrates  the  spectra  of  the  alkali-metals  with  their  char- 
acteristic rays.  These  rays  are  the  more  visible  in  proportion 
as  the  flame  is  less  luminous  and  its  temperature  higher.  The 
ordinary  Bunsen  gas-burner  answers  admirably  for  these  experi- 
ments. The  rays  shown  by  the  chlorides  of  potassium,  sodium, 
and  lithium  are  perfectly  well  defined  :  those  of  barium,  stronti- 
um, and  calcium  are  more  complicated,  and  require  a  somewhat 
experienced  eye  for  their  identification.  They  are,  however, 
quite  distinct  enough  to  be  easily  recognised,  even  when  salts 
of  these  metals  are  mixed  together  ;  for  the  great  advantage  of 
this  method  of  analysis  is,  that  foreign  matters  have  no  influ- 
ence on  the  results,  the  authors  being  able  to  detect  with  cer- 
tainty the  different  elements  in  a  mixture  containing  the  tenth 
of  a  milligramme  of  the  metals  mentioned  above.    Sodium,  with 
