43:2 Mr. Thomas Richardson on Donium, a 



dry matter, when treated with dilute muriatic acid, effer- 

 vesced, but did not dissolve, and its colour was changed 

 to white. After ignition, it was found to have a specific 

 gravity of 4-30.9. 



The substance which has thus been obtained from David- 

 sonite, and examined in detail, appears to be possessed of 

 properties different from any hitherto known. From the 

 alkaline and earthy bases, and from several of the metallic 

 ones, it is eminently distinguished by the green precipitate 

 which it gives with sulpho-hydrate of ammonia ; while its 

 solubility in the caustic alkalies, and in carbonate of am- 

 monia, the light brown precipitate thrown down by sul- 

 phuretted hydrogen, and the green given by sulpho-hydrate 

 of ammonia, are amply sufficient to distinguish it from all 

 the others. 



If this substance be considered as sufficiently distinct, 

 which, from its characters, I think I am warranted to 

 conclude, I shall propose to give it the name of Donium, 

 being a convenient contraction of Aberdonia, the Latin 

 name of Aberdeen, near which place Davidsonite occurs ; for 

 the suggestion of which name I am indebted to Dr. Thomson. 



The change of colour which the precipitates of this sub- 

 stance undergo, during the process of washing, appears to 

 be owing to different degrees of oxidation ; and with a view 

 to determine, if possible, the characters of the metal itself, 

 as well as its degrees of oxidation, the following experi- 

 ments were made : 



A. Over a portion of the white oxide strongly heated to 

 redness, in a green glass tube, a current of dry hydrogen 

 gas was passed, for nearly an hour. The whole was con- 

 verted into a slate-blue mass, while aqueous vapour was 

 evolved at the end of the tube : 100 parts of the white pow- 

 der, by this means, lost 16*34 of their weight. 



B. A portion of the buff oxide was treated in the same 

 way, and the same slate-blue powder was obtained, with 

 the evolution of aqueous vapour : 100 parts of this oxide 

 lost, by this process, 5-11 of their weight. 



The substance possessing the slate-blue colour exhibited 

 the following characters : 



1. When pounded in a dry agate mortar, it appeared to 

 asume a lustre, resembling the metallic. 



