* 
£ 
R. H. Lee—Atomic Weights of Cobalt and Nickel. 45 
Pure metallic cobalt was prepared by igniting chloride of 
purpureocobalt in hydrogen. ‘The metal was then dissolved in 
chlorhydrie acid and precipitated by sodic carbonate. The 
carbonate was washed, and then digested with oxalic acid, the 
resulting oxalate again washed, burned in a current of oxygen 
and the oxide reduced by hydrogen. In other portions of the 
oxalate the carbon was decried by combustion with cupric 
oxide. 
The following table gives a summary of the results obtained : 
Oxalate taken. Cobalt found. Carbon found. Equivalent €o. 
Ae ase 32°552 pr.ct,  'B0?4P% — o9.998 
ered 32-619“ ee 30°015 
3. ae 32°528 aOO8: 30-014 
en 2 oe ee eee 
: Mean, 30-003 
Determinations of the atomic weights of cobalt and nickel 
were also made in 1 y Marignac.* Cobaltous sulphate 
was purified by repeated crystallization and a weighed quan- 
tity of the salt heated so as to expel the acid. The resulting 
oxide was then heated with a known weight of silicate of lead 
so as to expel the excess of oxygen over and above that re- 
quired to form cobaltous oxide €00. The results obtained 
varied between 29°32 and 29°38. 
Crystallized cobaltous chloride dried at 100° was found to 
retain one atom of water. Three determinations of the chlo- 
rine in this salt by means of silver, gave for the atomic weight 
of cobalt 29-42 to 2951. Anhydrous cobaltous chloride was 
obtained by heating the crystallized salt with sal-ammoniac, in 
a current of dry chlorine or dry chlorhydric acid gas. The salt 
almost always however left a slight residue insoluble in water. 
Five analyses of the anhydrous salt gave results varying from 
29°36 to 29-42. ; 
In 1859 Dumast turned his attention to the subject. Per- 
fectly pure metallic cobalt was dissolved in nitro-muriatic acid, 
the solution evaporated to dryness with frequent additions of 
chlorhydric acid, and the cobaltous chloride submitted to a red 
heat. In a second preparation from a different sample of metal 
the chloride was dried in vacuo. In this manner the following 
results were obtained : 
* Bibliothique Universelle de Geneve, Nouvelle series, vol. i, p. 373. 
+ Ann. de Trae et de Physique, 3d series, vol. lv, p. 148. 
