Trap Dykes in the Sienke of Amhoor* 



305 



has been collected, I will conclude this paper with a few observations 

 deduced from it. 



Crj^stallization being an arrangement of the ultimate particles or atoms 

 of the crystallized body, according to certain definite laws, it is thence 

 evident that these atoms are of determinate bulk, and that matter cannot 

 in consequence be regarded as infinitely divisible, but must ultimately 

 arrive at a limit. What this limit is we know not, bat when it is attain- 

 ed, the atoms have also determinate figures, as well as bulk ; for it is 

 known, that certain crystals can only be built up complete by the con- 

 tinued addition of those elements hose form is fixed. Magnitude and 

 form necessarily imply density, and it is known that the particles of a 

 body, however dense that may be, are not in actual contact, but are sepa- 

 rated from each other by indefinitely small spaces. Now, considtiring 

 electricity as a fluid of the highest state of elasticity, M. Mosotti of 

 Corfu conceives, that these minute spaces are filled with the electric 

 fluid, so that each particle is confined within an atmosphere composed of 

 it. Fuither, and as consistent with the general phenomena of electricity, 

 he conceives that the atoms of the fluid repel each other ; the molecules 

 of the matter also repel each other ; while there is a mutual attraction 

 between the particles of the fluid and of the matter. Few indeed could 

 follow the refined and elaborate analysis by which M. Mosotti has suc- 

 ceeded in adjusting these forces, but we can ail understand and follow 

 the conclusions at which he has arrived. He has proved that with' 

 in certain limits the particles of bodies repel each other, the force 

 of repulsion diminishing rapidly as the distance increases — beyond a 

 certain limit the force becomes attractive, and hence there must be some 

 point at which equilibrium between these two forces exists, and there is 

 then no tendency either to repulsion or attraction ; if therefore we attempt 

 compression, the repulsive force resists, if we attempt disruption, the 

 attractive force or the force of cohesion then comes into play. The limit 

 at which the negative force becomes positive varies according to tem- 

 perature, and to the nature of the molecules, and determines whether the 

 body is to be solid, fluid or aeriform. Beyond the neutral point, the 

 attractive force increases till it attains a maximum, and then dimi- 

 nishes, till as soon as the particles are separated by sensible distances 

 it varies directly as the mass, and inversely as the squares of the dis- 

 tances — the well known law of universal gravitation. 



Such are the results of M. Mosotti's profound investigations :— -applying 

 them, therefore, to the case before us, viz. crystallization, it is evident, 

 that the form of the ultimate particles would materially influence the di- 

 rection of the attractive and repulsive forces j and hence arises our con- 



