[ 22 J 



Thefe fads being duly confidered, we fhall not be furprifed 

 at feeing the clofe vitreous texture deftroyed by the flow cooling 

 of melted whins (all of which contain the above ingredienis) 

 and fucceeded by the loofer texture of a mere ftony fubftance. 

 This is the only change that takes place, if we except the mi- 

 nute and indeterminate cryftallizations that occur in the cavities 

 formed by the expulfion of air v;hile the mafs was as yet foft, 

 for the facettes interfperfed through the flone cannot be ac- 

 counted cryftals, but only the rudiments of cryft-illization. Thefe 

 are formed at the inftant the affinity of the alkali is lefTened 

 and the earths begin to affume their folid ftate. The alkali being 

 as yet liquid, allows the earthy particles to move through it, 

 and to form thefe incipient cryftallizations. 



We are now to examine how far the ftony ftrudure aft*umcd 

 through flow refrigeration, by ftones previoufly fufed, tends to 

 afford any fupport to the Huttonian theory. In my opinion 

 it affords none at all ; the utmoft effed it can produce in an 

 unprejudiced mind is to render the origin of whins ambiguous 

 by making them affume the appearance of a Neptunian origin, 

 when in fa6l they owe it to fufion ; but it is only an appearance^ 

 for natural whins are accompanied with circumftances and con- 

 tain fubftances which contradid that appearance, and prove it 

 to be deceitful. Befides, thefe experiments have no relation what- 

 foever to granite or calcareous maffes which form the bulk of 



the 



