30 FORMS OF CRYSTALLINE BODIES. 



honeycomb, assuming the hexagonal arrangement" so conve- 

 nient to the economy of space, so accurately described, in his 

 lectures before the College of Surgeons, by Sir Antony Car- 

 lisle, 1818. 



The development of particular forms in the crystallization 

 of saline bodies, exhibits the undeviating prevalence of an 

 innate law of conformation : thus Epsom salt (sulphate of mag- 

 nesia) assumes the four sided prism : common salt, muriate 

 of soda, the cube, nitre (nitrate of potass), six-sided prism, 

 and alum, sulphate of alumina, octahedria, &c. 



The natural assumption of the spherical form by all liquids, 

 and all metals in a state of fusion, indicates that the sphere is 

 the primary form of the atoms of matter, and the comparative 

 volume of such spherical atoms with each other correspond in 

 a ratio with their densities respectively ; thus the SPHERICAL 

 drop of water is of proportionally greater bulk than that of 

 sulphuric acid, or mercury, &c. 



With respect to the transition from the sphere to the cube 

 or angular form in solids, and the exertion of the attraction of 

 cohesion of one cube, &c._, to another, vertically and laterally, 

 it must depend on the opposite states of the electricity of the 

 surfaces towards each other ; the points of original combination 

 are the poles of the spheres, but once joined and having assumed, 

 as to the corpuscles, the form appropriate, the electrical in- 

 fluences appear to extend over the whole of the surfaces in 

 contact, producing moderate cohesion. 



The depositions of congealed water on glass windows being 

 sometimes arborescent and varied in a most beautiful (but to 

 us apparently irregular and capricious) shape, must yet be 

 governed by electrical influences, modified by the breezes by 

 which they are usually accompanied. 



The electrical currents in mineral strata seem also to pro* 

 mice similar developments in the conformation of native 

 metallic depositions. 



I observed many years since some curious specimens of 



