The Atomic Weight of Radium. MME. CLRIE. Compt. rend., 145, 422; Chem. News, 96,127. —A redetermination of the atomic weight of radium was made using 0.4 gram of pure radium chloride. The purification process consisted, as in the previous determination, of fractional crystallization from water containing HC1. To guard against the formation of radium sulphate, which increased the difficulty of purification, all the reagents used had to be specially purified to remove the last traces of sulphuric acid. The method employed for the determination of the atomic weight was the same as previously used. It consisted in estimating, as silver chloride, the chlorine contained in a known weight of the anhydrous radium chloride. Three determinations, all of which agreed closely, gave for the atomic weight of radium, the mean value 226.18 (H —1) or 226.45 (O—16.00), assuming that radium is a bivalent element. The value previously found was 225. The author attributes the difference in the numbers to less pure reagents used in the older determinations, and to inferior accuracy of the experiments which were performed with only 90 mg. of radium salt. W. H. Ross.
1867-1934
3:130 CA Vol. 3, 1909
iJ%W^:\\^ ^ w i . , % ^ ^ w J l
§Bfa3r\&
8t « ^ ^ ^\^;>/i$- V|l^ v /i'fe/S ^%fej
A K £ 11\
