URANIUM. 267 



Zimmermann's second method was essentially that of Wertheim, 

 namely, the ignition of the double acetate U02(C2H302)2.NaC2H302, the 

 residue being sodium uranate, Na^UjO^. 



Double Acetate. Uranate. Per cent. Uranate. 



4.272984 2.886696 67.557 • 



5.272094 3.560770 67.540 



2.912283 1.967428 67.556 



3.181571 2.149309 67.555 



Mean, 67.552, ± .0027 

 Wertheim found, 67.523, ± .0076 



General mean, 67.549, rt .0025 



All the data for uranium now sum up thus : 



(i.) Per cent. UOj from uranyl oxalate, 71.782, zb .019 



(2.) 6CO2 : UgOg : : lOO : 321.443, ± .338 



(3.) Molecular weight of uranyl acetate, 423.842, ± .4222 



(4.) 3UO2 : U3O8 : : loo : 103.9276, d= .0003 



(5.) Per cent. Na^UjO, from U02.Na{C2H30.2')3, 67.549, i: .0025 



Computing with = 15.879, ± .0003 ; C = 11.920, ± .0004, and Na = 

 22.881, ± .0046, we have— 



From (I) = 235.948, ±.1938 



From (2) " = 238.462, ± .2953 



From (3) " = 238.541, ± .4223 



From (4) " = 237.770, ± .0055 



From (5) " ^ 237.902, ± .0283 



General mean U = 237.774, ± .0054 



If == 16, U = 239.586. 



In this case Zimmermann's data control the final result. All the other 

 determinations might be rejected without appreciable effect. 



