ALL MATTER, TOXDERARLE AND IMPONDERABLE. 283 



But if the dimensions of molecules are extremely smtill, the distances which 

 separate them are relatively very great, insomuch that, accordiug to the sugges- 

 tive idea of Laplace, a molecule may he compared to a star, and moleculur gravi- 

 tation to universal gravitati<m. It results from this that the movements of mole- 

 cules may be compared to the movements of the stars, and it is thus that mod- 

 ern physics has raised itself to the height of mechanics. It is interesting to see 

 a Solid body suddenly obey the laws of attraction at the moment when it enters 

 within the sphere of influence of a liquid ; the etfect is still produced when the 

 liquid does not moisten the solid. 



Cohesion, which may be considered a modification of gravitation, acts with 

 difierent degrees of intensity on diderent bodies. All the degrees of intensity 

 which separate the least dense fluid from the most condensed solid, form only 

 some of the intermediate terms of an indefinite series, of which the ultimate parts, 

 eminently solid, the ponderable atoms represent one of the extremities ; at the 

 other are found the matter of the nebulae and th(? molecules of the ether itself. 

 It is these ponderable atoms, subject as they all are to the attraction of the 

 neighboring atoms and to that of the ether which surrounds them witli a species 

 of atmosphere, that produce thermal, electrical, and optical phenomena. 



Under the relatively variable influence of these phenomena, l)odies must con- 

 tinually undergo modiiications in their internal structure. In effect, what varie- 

 ties of forms invest quartz and feldspar in their slow and gradual i)assago from 

 a vitreous to a tophaceous state ! And not only stones, originally resistant, which 

 become friable, but ilexible substances which be(M)me more and more rigid ; cal- 

 careous concretions which from afibrous texture acipiire a lamellar texture ; siliceous 

 incrustations, primitivel}' friable, which are transformed into afi!)rous tissue, &c. ; 

 are there not here positive proofs that, even in the most compact bodies, the mole- 

 cular grouping undergoes incessant transformations"? In these continual trans- 

 formations, we cannot neglect the action of gravitation. Pictct has evinced it 

 by showing the shortening which a metallic rod undergoes by resting vertically 

 on its lower extremity. It is known, also, that the sheets of lead with which 

 the roofs of certain buildings are covered grow thiinicr with time in their upper 

 part, and become denser in their lower part. Ileucc it results that the particles of a 

 metal tend, like those of a liquid, to place themselves on a level, by yielding 

 slowly, but in a continuous manner, to the force; of terrestrial gravitation. 



Oil placed in a mixture of water and alcohol, having the same density with 

 itself, is subject only to the molecular attraction of its own matter, and of the 

 medium in which it displaces its bulk without mingling therewith. It maintains 

 itself in equilibrium and keeps tla; position in which it is placed ; being thus 

 withdrawn from the terrestrial gravitation, it takes tin; spherical form which sat- 

 isfies all the conditions of a force acting (■(pially in all directions. 



Among the expedients which enabled M. Plateau to obtain a certain nmnbet 

 of geometrical iigures under the influence of the molecular attraction, I will cite 

 one which led to effects truly curious. If, through one of the small spheres of 

 oil i)laced in a mixture of water and alcohol, we pass a small metallic rod, 

 to which we communicate a rotary movement, this movement is suddenly trans- 

 mitted to the whole mass of oil. The little sjdiere, by virtue of the. centrifugal 

 force, becomes flattened in i)ro[)ortion as it revolves more rapidly. Such is also 

 the cause to which we usually attribute the flattening of the terrestrial sphere. 

 When we continue to increase the velocity of rotation, the flattening is cidianced 

 to such a degree that the s[)liere grows hollow, and of a siulden separates into 

 two parts: the interior part, which is a si)here, remains at the centn? of the sec- 

 ond i)art, which has the form of a ring. It is impossibh; to witness th(^ forma- 

 tion of this ring without recalling that of Saturn, which doubtless nnist hiivo 

 formed itself after the same- manner. Thus the same cause which gives rise to 

 the limpid drops of dew which sparkle on the leaves of plants, and which com- 



