548 Intelligence and Miscellaneous Articles. 



from the Coniston Flags and Grits, the uppermost division of the 

 formation : — Graptolithus Ludensis, Diplograpsus pristis, Phacops 

 obtusicordatus , Orthis crispa, Cardiola interrupt a, Orthoceras filosum, 

 0. tenuistriatum, and 0. subannulatum. 



4. " On the Lower Silurian Rocks of the Isle of Man." By 

 Prof. R. Harkness, F.R.S., F.G.S., and H. Nicholson, Esq. 



The older sedimentary deposits, which occupy the greater part of 

 the island, have been regarded by previous observers as Lower 

 Silurian. These slates were described by the authors as forming an 

 anticlinal axis which traverses the island in a north-east and south- 

 west direction, and to be conformably overlain at Douglas Head and 

 Banks How on the south-eastern part of the island, by green ash- 

 beds (slates and porphyries). 



The only fossil of the slates is the JPaheo chorda major of the 

 Skiddaw slates ; and from the circumstance that the Lower Silurian 

 rocks of the Isle of Man are in the exact line of strike of the Skiddaw 

 slates of the Lake-country, the authors regarded these beds as cor- 

 responding with them; and the "green ash-beds" were considered 

 to be the equivalents of the ash-beds and porphyries which succeed 

 the Skiddaw slates. 



LXXIX. Intelligence and Miscellaneous Articles. 



ON THE LAW OF THE UNION OF SIMPLE SUBSTANCES, AND ON 

 ATTRACTIONS AT SMALL DISTANCES. BY MM. ATHANASE AND 

 PAUL DUPRE. 



nPHE use of weighings in measuring work and molecular forcesleads 

 to a precision which had not been hitherto attained. It has be- 

 come possible to commence the study of attractions at small distances ; 

 and there is reason to hope for an early and considerable progress 

 in those branches of the physical sciences which are more directly 

 connected with molecular mechanics. 



When two bodies, terminated by plane parallel faces, approach till 

 they are in contact, a work is effected proportional to the surface, 

 and independent of the thickness, provided this exceeds the radius e 

 of the sphere of sensible attraction. We have shown that the same 

 number represents this work, the force of union, and the force of 

 contraction of the superficial layer ; the apparatus for determining 

 it have been described (memoir addressed to the Academy in October 

 1865, and Annates de Chimie et de Physique, February, March, and 

 April 1866). If reduced by calculation to the unit of surface and 

 unit of specific gravity, the result obtained for each body becomes 

 comparable with analogous numbers. The two plates which unite 

 may moreover be of the same nature, or may have a different che- 

 mical composition ; it is convenient to represent the force of union 

 by a symbol/ accompanied by a chemical indication of the bodies 

 in question; thus/JJ° represents the force of the union of mercury 

 with itself after reduction to unity, and/2 that of hydrogen with 

 oxygen. By the aid of this notation the force of union of a com- 



