162  A  Piece  of  Pitchblende.  {AmAprii\909arm' 
gave  the  name  uranium,  after  the  planet  Uranus,  then  recently  dis- 
covered by  Herschel. 
I  may  mention  here  in  passing  that  the  art  of  chemical  analysis 
was  in  those  days  almost  monopolized  by  your  profession,  and  that 
many  of  the  most  important  chemical  discoveries  of  the  eighteenth 
century  must  be  credited  to  pharmacists. 
But  neither  Klaproth  nor  his  contemporaries  who*  investigated 
the  new  metal  succeeded  in  obtaining  it  in  the  free  or  elemental 
state.  This  was  not  accomplished  until  1840,  when  the  French  chemist 
Peligot  demonstrated  that  the  supposed  metal  was  really'  an  oxide 
and  that  its  isolation  requires  special  means  to  remove  the  oxygen. 
Thanks  to  his  researches  and  those  of  Roscoe,  Zimmermann  and 
others,  we  are  now  as  familiar  with  this  rare  element  as  we  are  with 
the  more  common  elementary  bodies.  Its  peculiarities  and  idiosyn- 
crasies have  been  duly  noted  and  recorded,  and  its  proper  place  in 
the  natural  families  of  elements  definitely  established. 
Moissan  has  taught  us  how  metallic  uranium  can  readily  be  pro- 
duced by  the  reduction  of  its  oxides  in  the  electric  furnace.  We  can 
also  effect  its  reduction  by  the  Goldschmidt  process,  that  is  by  the 
aid  of  metallic  aluminum.  I  am  not  aware,  however,  that  metallic 
uranium  has  found  any  practical  applications.  "It  is  in  the  form  of 
compounds  that  uranium  is  extracted  from  pitchblende  at  Joachims- 
thal,  the  products  being  highly  prized  as  pigments  in  the  manufac- 
ture of  glass  and  for  decorating  china.  The  uranyl  compounds  are 
characterized  by  a  fine  yellow  color  and  a  strong  green  fluorescence. 
This  piece  of  uranium  glass,  for  instance,  is  yellow  in  transmitted 
light,  but  shows  a  beautiful  green  color  on  the  surface.  Here  are  a 
number  of  uranyl  minerals  and  salts,  all  of  which  show  this  peculiar 
phenomenon.  This  black  substance  is  an  oxide  of  uranium  employed 
in  china  painting. 
The  chemical  processes  by  which  the  uranium  products  are  manu- 
factured at  Joachimsthal  are  rather  complicated,  and  it  would  hardly 
interest  you  to  know  the  details.  Essentially  the  treatment  consists 
in  calcining  a  mixture  of  the  roasted  and  powdered  ore  and  soda, 
washing  the  yellowish-brown  mass  resulting  from  this  operation  with 
hot  water,  and  then  extracting  it  with  dilute  sulphuric  acid.  The 
solution  so  obtained  contains  the  bulk  of  the  uranium,  which  is 
further  converted  into  the  desired  compounds,  such  as  the  yellow 
uranates  of  sodium  or  ammonium,  and  the  black  oxide  of  uranium. 
The  insoluble  residue  was  formerly  cast  aside  as  a  waste-product, 
