VOL. LXXXI.] PHILOSOPHICAL TRANSACTIONS. 13 



cesses for glass-making an homogeneous product is obtained from heterogeneous 

 materials, we conclude, that an heterogeneous product may not, under other cir- 

 cumstances, result from fusion ; and that fire keeps inseparably blended whatever 

 it has once reduced to a uniform liquid paste. 



It must also be carefully remembered, that this difficulty does not press the 

 igneous more than the opposite hypothesis. Since the constituent parts of granite 

 are crystals, the whole mass must once have existed in that state of entire disunion 

 of its particles which is necessary to crystallization. Now, whether such a solu- 

 tion have been effected by the repulsive power of fire, or the intervention of 

 water, it is just as easy to conceive heterogeneous earthy crystals shooting from 

 difi^erent points of a uniform liquid, according to the former supposition, as the 

 latter. 



In the natural history of granite and basaltes, another striking circumstance 

 occurs : they lie so contiguous, and are so involved in each other, that we can- 

 not but suppose both to have undergone the same operations of nature at the same 

 time. This is seen with the utmost frequency on every possible scale, and under 

 a vast variety of modifications. The facts already quoted afibrd instances in 

 point. Dr. B. had before him a specimen from the park of Stockholm, consisting 

 partly of trap and partly of granite. The adjacent parts are as firmly united as 

 the other parts of the specimen ; and when a violent blow is struck, the trap 

 and granite do not separate, but the fracture takes some other direction. They 

 seem in several places of the boundary to run into each other. The whole 

 mountainous district surveyed by Mr. Leske with such scrupulous accuracy 

 affords multiplied examples of the contiguity and connection between these differ- 

 ent rocks. " From all these minute descriptions," says the author, " it appears, 

 that the base of the whole range consists of granite. On the declivity of the 

 highest elevations, and on the solitary summits of the external chain, corneous 

 porphyry lies on the granite, out of which as well as the granite itself, and the 

 sandstone at its foot, basaltes has been protruded by the force of subterraneous 

 fire." The manner of connection will appear from a few examples. The basaltes 

 of the Spizberg has a granulated structure, and is imbedded in granite. The 

 substance of the pillars of the Gikelsberg is close and granular : in some pieces 

 " the constituent grains of granite are little altered." Of the columns of the 

 Knorberg, " the substance is close, uneven, and consists of distinct grains : . , . 

 large pieces of imperfectly fused granite are diffused through its substance. In 

 the Whinstone of the Hochwald there are found pieces consisting of a mixture of 

 white feldspath, quartz, and black shoerl." Again, in the Rauberg, the con- 

 stituent parts of granite are so diffused through the basaltes, that the author 

 imagines the rock to be an imperfectly fused granite. Dr. B. rather considers 

 these as instances of imperfectly crystallized granite, where some unfavourable 



