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XVII. On the Atomic Weight of Glucinum ( Beryllium). 
By T. S. Humpidge, Pli.D., B.Sc. 
Communicated by Professor E. Frankland, F.R.S. 
Received Marcia 20—Read April 12, 1883. 
[Plate 45.] 
I. Introductory. 
Ever since the discovery of glucinum by Vauquelin, in 1798, its atomic weight 
has been a disputed matter amongst chemists.. Its discoverer considered that its 
oxide was a monoide, an opinion which w T as however strongly opposed by Berzelius, 
who wrote the oxide G1 2 0 3 and the atomic weight 13*7 (0 = 16). The researches of 
Awdejew" and DebrayI again turned the scale in favour of the earlier view, and as 
an atomic weight of 9'2 suited the properties of the metal in the tables of periodicy 
constructed by MM. Mendeleee and Lothar Meyer, this atomic weight has, up to 
quite recently, been generally accepted by chemists. As a welcome confirmation to 
this came a determination of the specific heat of the metal by Professor E. Reynolds,;); 
who found that for its atomic heat to be near the normal number 6'0, its atomic weight 
must be 9'2 and not 13'8. Almost immediately afterwards a second determination of the 
specific heat was made by MM. Nilson and Petterson,§ who, however, obtained a 
result agreeing not with the lower atomic weight but with the higher. 
The reasons for these conflicting opinions are to be found—first, in the anomalous 
position of glucinum among the elements; secondly, in the difficulties ’which surround 
the preparation of even small quantities of the free metal in a tolerably pure condi¬ 
tion ; and thirdly, in the fact that no volatile compound of glucinum is known of which 
the vapour density might be easily determined. 
The constitution of the compounds of glucinum cannot be inferred from any physical or 
chemical similarities with analogous compounds of other metals. Its compounds most 
closely resemble those of magnesium and aluminium, but also differ from these in the 
most striking manner. None are isomorphous with any similar compounds of these 
\P0GG. Ann., lvi., 101. 
f Ann. Claim, and Plays. [3], xliv., 5. 
J Phil. Mag. [5], iii., 38 ; Chem. News, xlii., 273. 
§ Berl. Ber. xi., 381, 906. 
