26 Mr. T. Bayley on the Atomic Weight and the 



the matter, and make no such pretension; their whole interest 

 lies in the visible, ocular demonstration they afford of the 

 truth of conclusions long ago worked out by the brilliant 

 mathematical genius of Fresnel. But to the best of my 

 belief they are new ; and if it should prove that some other 

 student has been before me, I hope the beauty of the pheno- 

 mena may excuse my bringing them before you. 



III. On the Connexion between the Atomic Weight and the Che- 

 mical and Physical Properties of Elements. By Thomas 

 Bayley*. 



[Plate II.] 



WHEN we arrange the elements in the order of the atomic 

 weights, hydrogen of course comes first. After this 

 there is a considerable interval, corresponding to an increase 

 of six in the atomic weight, before the next element, Avhich is 

 lithium. After lithium the elements follow in this order, — 

 beryllium, boron, carbon, nitrogen, oxygen, fluorine — the rise 

 in atomic weight between each being on an average about 

 two. The next element is sodium, with the atomic weight 23; 

 and after sodium come magnesium, aluminium, silicon, phos- 

 phorus, sulphur, chlorine — the average rise in atomic weight 

 being again about two. If we stay to consider the properties 

 of the elements we have so placed in sequence, our attention 

 is soon arrested by some curious circumstances. Excepting 

 hydrogen, separated as it is by so great an interval from all 

 other elements, lithium is the first. Lithium is a metal of 

 the alkalies, which is only another way of saying that it has 

 properties exceedingly like those of the well-known metals 

 potassium and sodium. It is metallic, strongly electropositive, 

 and chemically active, and of low specific gravity; it forms 

 an oxide and salts which are soluble in water, and formed by 

 the union of the metal with the smallest proportions of oxygen, 

 chlorine, OT other negative radical, simple or compound, that 

 are found to be capable of reacting chemically. The next 

 element (beryllium), although its atomic weight is greater 

 than that of lithium only by two, has very different properties. 

 It is metallic, electropositive, and chemically active; but its 

 oxide is insoluble in water, and the metal unites with two 

 atoms of chlorine or bromine to form its halogen compounds 

 instead of with one. The succeeding elements have no longer 

 the metallic character, which, however, has not quite disap- 

 peared in the case of boron, the next in succession. Carbon 



* Communicated by the Author. 



