Weight of Beryllium. 71 



regard beryllium as a triad, lithium must also be regarded as 

 a dyad (Li // = 14 ? oxide LiO) and as a member of the alka- 

 line-earths group ; for that metal forms, as is well known, 

 a difficultly soluble phosphate and carbonate and no stable 

 hydrosulphate or hydro carbonate, its oxide combines only 

 slowly and with a slight development of heat with water .to 

 form a non-deliquescent hydroxide, its nitrate and chloride 

 are soluble in alcohol-ether and very deliquescent, the metal 

 cannot be reduced by charcoal, &c. 



But all those reactions, as well as the reactions of beryllium, 

 are completely explained by the three above-mentioned equa- 

 tions of the position of lithium and beryllium. 



(7) The circumstance that beryllium forms double fluorides 

 finds its explanation in the feeble basic properties of beryllia. 



(8) Also the easy volatilization of beryllium chloride may 

 be easily deduced from the above equations (b) and (c) with- 

 out it being necessary to assume the formula Be 2 C] 6 for it. 



(9) The isomorphism of beryllium oxide with alumina is 

 of no importance, as ZnO and Zr0 2 crystallize in the same 

 forms. But also the salts of lithium are not isomorphous with 

 those of sodium, any more than those of Be and Mg, or B 

 and Al. 



Repeating shortly what has been said, it follows that in all 

 probability the atom of beryllium is Be'' = 9*1, and its oxide 

 BeO, from 



(1) the molecular volume of beryllia, 



(2) the molecular volume of its sulphate, 



(3) the molecular heat of the earth, 



(4) the atomic heat of the oxygen contained in it, 



(5) from the chemical nature of beryllium. 



The numbers which refer to this formula do not stand, as 

 Messrs. Nilson and Pettersson would have us believe, without 

 analogy in the whole domain of chemistry ; on the contrary, 

 they exactly correspond to the position of dyad beryllium in 

 the periodic law. Moreover they find a complete analogy in 

 the element lithium, so far as the physical properties of the 

 compound of this metal have been investigated. They give a 

 new confirmation of the view that beryllium forms, like eleven 

 other elements with a small atomic weight, an exception to the 

 law of Dulong and Petit. 



Owens College, Manchester, 

 December 14, 1880. 



