310 SirJamis Hall on the Consolidation of the Strata, [Oct# 



evident traces of iron, the rock being stained in a great variety 

 of ways ; sometimes in parallel layers, — sometimes in concentric 

 circles, or rather in portions of concentric spheres, like the coats 

 of an onion, — and, generally speaking, disposed in a way not 

 accountable by deposition from water. All these appearances 

 I would account for, by supposing the rock, either at the moment 

 of its agglutination into sandstone, or at some subsequent 

 period, to have been penetrated by the fumes of salt, charged 

 with iron, also in a stale of vapour. 



I may mention one very curious result of my experiments 

 with salt and iron, acting upon sand, namely, that, upon break- 

 ing up the specimen of artificial sandstone, an appearance often 

 presents itself of incipient crystallization, if I may use this 

 term ; a number of large, shining, parallel faces pervade the 

 whole mass, and, by holding the specimen at the proper angle 

 to the light, this appearance becomes very obvious. What the 

 nature of these crystals is, I have not investigated; but as they 

 very much resemble what we see in different kinds of sandstone, 

 I am of opinion that they hold out a fair expectation, of our 

 being able to produce many of the crystalhne appearances with 

 ■which we are familiar in nature. 



Common sea-salt, such as I have used, as is well known, is 

 not pure muriate of soda; and, in my ex!periments, I have mixed 

 various other substances with it. In Nature, we must suppose 

 that various contaminating substances would in like manner 

 occur, to diversify the phsenomena ; and, accordingly, we do 

 find a boundless variety, in the aspect not only of sandstone, 

 but of almost every kind of rock ; and I am by no means with- 

 out expectation, that, in the course of time, we shall be able to 

 imitate in our laboratory as many of these varieties as we choose 

 to exhibit. 



I have long been engaged also in a series of experiments on 

 the fonnation of Crystallites^ the name by which, as I have 

 before stated, every crystallized rock might, perhaps, be usefully 

 distinguished in contradistinction to Aggregates, or those formed 

 of fragments. This great object in experimental geology, I 

 hope to accomplish by means of an instrument which I have 

 long had in use, for the regulation of high heats, a description 

 of which may probably soon be laid before the Society, together 

 with some further results in support of the Huttonian Theory of 

 the Earth. 



