JCfcMATlON OF BASALTE*. 27l 



not their results to bear the stamp of this uniformity of cir- 

 cumstances ? Do not the cracks of clay dried by a scorching 

 sun sometimes exhibit polygons nearly, regular? Do not the 

 cracks in the glaze of pottery, which superficially examined 

 appear destitute of symmetry, resemble on closer inspec- 

 tion a kind of mosaic issuing from the hand of a single. ar- 

 tist? 



Mr. Patrin even mentions a piece of ancient enamel in Regular cr*ck$ 

 the collection of Mr. Dolomieu, the surface of which exhi- )> m d c»vstaUi- 

 bits throughout hexagonal figures, representing in miniature zation. 

 a horizontal section of a basaltic causeway. But who can 

 conceive with him, that these hexagons are the effect of crys- 

 tallization? Is it not evident, that the metallic base, on 

 which the enamel rests, being capable of greater dilatation, 

 may under various circumstances have occasioned cracks* 

 the unusual regularity of which gives at first sight an erro- 

 neous idea of their causes? 



The basaltic prisms then are the result of a regular con- The cooling of 

 traction, and the hypothesis of Dolomieu, which ascribes it i^tcTbv °^ 

 to a refrigeration accelerated by the contact of a body that something 

 quickly imbibes caloric, agrees perfectly with the division of JjSort^we 

 the sandstone of Mr. Chevaillers, the surface of which is co- 

 vered wifh a scorified metallic stratum serving as a conduc- 

 tor to the caloric. 



If geologists be not agreed on the formation of basaltes, Caloric aa^ 

 they cannot refuse to admit, that caloric performs one of formation. 

 the principal parts in it; whether it act alone, or in concert 

 with other solvent gasses, known or unknown to naturalists: 

 and the latter, as they are extricated, may furnish analogous 

 results. 



When a body is strongly heated, if the action of caloric Effects of * 



come to cease suddenly, the body experiences the most in- sudden cessa- 



J . • , tion of its 



tense degree or heat at the instant when the caloric escapes, agency. 



In fact, the caloric, rushing rapidly toward the body that 

 absorbs it in proportion to the strength of its affinity, ac- 

 cumulates on the parts which it traverses as a powder does a 

 sieve, and sets in motion the particles of the body, which al» 

 most at the same instant are briskly separated and left to the 

 attraction of cohesion, that tends to unite them. Spheres 

 ©f attraction are then established between the particles of 



caloric 



