to the size of their Molecules, fyc. 289 



the researches of M. Avogadro, of which we now propose to 

 give a brief account, promise to carry us still further among 

 the mysteries of elementary matter. 



In a preceding number, * we have already given some ac^ 

 count of a remarkable law announced by M. Kupffner, who 

 has endeavoured to establish a relation between the crystalline 

 form, the weight of the atom, and the specific gravity of bodies. 

 If //, for example, is the volume of its primitive form, the cube 

 of its axis of crystallization being unity, p its atomic weight, 

 and s its specific gravity, then, according to M. Kupffner, 



— = const. ; and, consequently, s is in the direct ratio of y> 



and the inverse ratio of p.f But this relation, as M. Avo- 

 gadro has remarked, is not indicated by any theoretical con- 

 sideration ; and, with regard to the facts upon which he rests 

 it, there is so much latitude in the relation of primitive forms, 

 and in the determination of the atomic weights, that there is 

 reason to believe, that any other arbitrary relation might, 

 by similar means, be made to agree with observation, and that 

 the one which he has adopted has no real foundation. 



MM. Royer and Dumas have endeavoured to show, that 

 the volume of the atom of all solid bodies is either equal 

 to, or represented by, a variable multiple of the smallest of 

 these volumes, or rather of an ideal unity, assumed as the 

 type of them all ; or, what is the same thing, that the densi- 

 ty of solid bodies is proportional to the mass of the molecule, 

 or to an aliquot part of this mass. But M. Atogadro is of 

 opinion, that this law is not established by the observations 

 they have brought to its support, and that it is liable to other 

 objections, which we have not room here to enumerate. 



The density of any body is, in general, necessarily in the 

 ratio of the mass of its integral molecules, divided by, the cube 

 of the distance of the centres of these molecules. In ductile 

 bodies, whose molecules may change their position without 

 separating, and in which, consequently, the figure of the mo- 

 lecules does not appear to exert any sensible influence, the 



• See this Journal, vol. iv. p. 186, — 188. 



+ In tlie Scientific Intelligence of this Number, we have given several 

 results, deduced by M. Vincent from Kupffner's Law, which are so re- 

 markable, as to render a farther examination of it very desirable. 



