153 



gradually propagate itself till the temperature of the glass is equal- 

 ized, and then the recurrence of the circumstances which induced 

 the first particles to arrange themselves will cause other particles to 

 arrange themselves also ; and these the attraction of aggregation will 

 dispose round the point first formed. A second emission of heat in 

 every direction will now take place ; the temperature will again be 

 equalized ; and again another concentric coat of arranged particles 

 will apply itself to the little globule. That these globules are formed 

 of concentric coats does not clash with the circumstance of their being 

 likewise radiated ; as every one may have remarked the connexion 

 that almost uniformly exists between the radiated structure and the 

 formation by concentric coats ; the more obvious instances of which 

 are the haematites and the calcareous stalactites. In what manner 

 this is likely to be effected is stated at some length in the paper. 



Some curious remarks are next made on the observation of Mr. 

 Smithson. that solution, far from being necessary to crystallization, 

 effectually prevents its commencement ; since, while solution sub- 

 sists, crystallization cannot take place : and many of the phenomena 

 being duly considered, it seems most probable that the particles of 

 bodies apparently solid must be capable of some internal motion, 

 enabling them to arrange themselves according to their crystalline 

 polarity while they are in a solid state. Among the instances given, 

 are the conversion of glass vessels into Reaumur's porcelain, the tem- 

 pering of steel, and the process of annealing. This does not alto- 

 gether disprove the crystallizations formed by molecules suspended 

 in aqueous solutions ; but it is in general insisted upon, that all cry- 

 stallizations are dependent on heat, there being, in fact, no fluidity, 

 and consequently no solution, which heat does not produce. 



These observations tend to prove the analogy which exists between 

 the igneous and aqueous formations, and to show that precisely the 

 same order and kind of arrangement is followed in the generation of 

 stony masses from water as from fire. Among the many instances 

 that are adduced to justify this assertion, are, on the one hand, the 

 phenomena exhibited by lavas, in which may be observed every step 

 of the passage from the vitreous to the stony, from that to a porphy- 

 ritic, and finally to the granitic state : on the other hand, we may 

 select the formation of calcareous stalactites, in which the successive 

 depositions of calcareous carbonate form a mass which at first is 

 fibrous ; a continuance of the process causes the fibrous structure to 

 disappear, and the stalactite becomes irregularly spathose; after 

 which the irregularities vanish altogether, and it becomes perfect 

 calcareous spar, divisible into large rhomboids, with the form pecu- 

 liar to that mineral. 



Adverting now to the chief object of this paper, the basalt, the 

 author observes, that should, in fact, the analogy between the aqueous 

 and igneous formation appear founded, the transition from glass to 

 stone can no way affect the great question which has so long divided 

 geologists about the origin of basalt : for though it be synthetically 

 demonstrated that basalt may be formed by fire, the proofs in favour 



