1883.] On the Atomic Weight of Glucinum {Beryllium). 137 



rotation of the earth on its axis are at least premature, until the 

 theories have been revised with a unit of time freed from changes of 

 adopted constants, which are at present inextricably mixed up with 

 any effects which would result from a change in the time of rotation 

 of the earth on its axis. 



II. " On the Atomic Weight of Glucinum (Beryllium)." By T. 

 S. Humpidge, Ph.D., B.Sc. Communicated by Professor 

 Frankla^d, F.R.S. Received March 20, 1883. 



(Abstract.) 



In this paper the author shows that no conclusions with respect to 

 the atomic weight of glucinum can be drawn from analogy of its com- 

 pounds with those of other metals, and that this long-disputed ques- 

 tion can only be decided by the specific heat of the metal or by the 

 vapour- density of some of its volatile compounds. Two determina- 

 tions of the specific heat have been made by Professor E. Reynolds 

 and byM. Nilson, the former of whom obtained a result of about 0*6, 

 and the latter only about 0"4. The probable inaccuracies in Professor 

 Reynolds' apparatus are pointed out, and it is shown that his metal 

 was probably impure. 



The author has prepared metallic glucinum from the chloride, the 

 vapour of which was passed over sodium contained in iron boats in a 

 glass tube. A metal was thus obtained which had the composition : — 



Gl 93-97 



G1 2 3 471 



Fe 1-32 



Si traces. 



100-00 



and was probably the purest yet prepared. 



The specific heat was determined by a modification of Regnault's 

 method of mixtures, using electrical appliances to avoid the necessity 

 of an assistant. Three determinations of the specific heat of silver in 

 water, made to test the apparatus, gave the following results : — 



I 0-05677 



II 0-05568 



III 0-05553 



Mean 0'05600 



and with a mean error of 1 per cent. The specific heat of metallic 



