2 URANIUM, ANTIMONY, CHROMIUM, &c. 



SECT. I. 



OF THE ATOMIC WEIGHT OF URANIUM. 



IT is sufficiently known, that uranium was dis- 

 covered by Klaproth, in a set of experiments 

 which he made on black blende, in 1789 ; that 

 the properties and some of the compounds of 

 uranium were examined by Bucholz, about the 

 beginning of the present century ; and that M. 

 Schonberg made a set of experiments in Berze- 

 lius' laboratory in 1813, in order to determine 

 its atomic weight. But by far the most elabo- 

 rate and instructive investigation of the proper- 

 ties of uranium and its compounds was made by 

 M. Arfwedson, and inserted by him in the Me- 

 moirs of the Stockholm Academy of Sciences for 

 1822. By the kindness of Mr. Heuland of Lon- 

 don, whose liberality I have so often experienced, 

 I was supplied with a sufficient stock of pitch- 

 blende, to enable me to procure the oxides of 

 this metal in such quantities as put it in my 

 power to repeat such of Arfwedson's experi- 

 ments as seemed to require examination, and to 

 determine the atomic weight of these compounds, 



Method of ^ trust, with considerable accuracy. 



obtaining Pitchblende obviously varies considerably in 



peroxide of * 



uranium, its composition, consisting, in fact, of a variety 



