MancJiestcr Memoirs, Vol. Hi. (1907), No. 1. 



I. "On the Atomic Weight of Radium." 

 By Henry Wilde, D.Sc, D.C.L., F.R.S. 



( Received and read October 2gth, igo'j.) 



In my paper read before the Society last year\ it was 

 shown from the relations of the specific gravities of the 

 alkaline-earth metals to their atomic weights, and also 

 from the similar relations of the series of alkaline metals, 

 that radium would have a proximate specific gravity of 

 5, and an atomic weight of 184, notwithstanding the 

 assertions that have been made that the new element 

 would be a heavy metal comparable with thorium 

 (sp. g. 1 1) and uranium (sp. g. 18), and that its atomic | 

 weight ranged between 225 and 258. It was also shown 

 that the atomic weights of the two series Hn and H2n of 

 my tables, are definite multiple differences and not intei'- 

 mediate mivibers. 



In the several accounts which have been given of the 

 atomic weight of radium, it is stated that the experi- 

 mental determinations were made with radium chloride. 

 Now it is well known to chemists that the series of 

 alkaline metals and alkaline-earth metals, magnesium, 

 calcium, strontium, and barium unite with chlorine in one 

 proportion only. 



An important gain to chemical science which the 

 multiple differences of the atomic weights have led up 



^ Manchester Me/noirsy vol. 51, No. 2, 1906. 

 November 2isf, igoy. 



