L. V. BELL'S ADDRESS. 585 



points demonstrable by the very youngest student in analytical 

 chemistry. They exist not as separate and disjunct ingre- 

 dients, but so combined together that their peculiar traits are 

 lost so far as external characteristics are concerned, in the com- 

 pound. For example, oil of vitriol and lime, both exceedingly 

 caustic, when united form plaster of Paris, whose extraordinary 

 inertness is well known. 



While the soil is made up of the dust or detritus of the rocks 

 under it, or as is much more common, of those \vhich have 

 been swept over the underlying ledge by some great diluvial 

 currents, (for soil without a trace of lime is often found resting 

 on limestone ledges,) of course the elementary ingredients 

 which entered into the rocks originally, will be found in the 

 soil, and are gradually brought into new combinations by their 

 effects upon each other, and especially as recently discovered, 

 by the galvanic or vital action of the roots of growing vegeta- 

 bles upon them. 



Take for example, our most common rock, granite. You 

 cast your eye upon its pepper and salt colored surface, and you 

 will have no difficulty in making out that it is composed of 

 three different minerals, stirred together as it were loosely, so 

 irregularly in fact, that all conditions of coarseness and fine- 

 ness exist. While in the fine, equable and good varieties, each 

 inch is tinted and arranged like each other inch, in the coarser 

 forms, pieces of one of the minerals as large as hogsheads may 

 be observed, and veins, streaks, and contorted dykes of what 

 elsewhere in the same stratum may be thoroughly incorporated 

 and uniform granite, are prominent. One of the components 

 of granite is quartz, resembling clear or smoky glass, the second 

 is the isinglass or mica, in scales usually of tiie size of the sec- 

 tion of a pin's head, but which may exist in plates five or six 

 feet square, and the third is the pearly lustred, opake, whitish, 

 or yellowish, or rose-tinted stone known as felspar. Now this 

 felspar contains, fifteen to twenty per cent, of potash, as pure 

 as any that ever passed inspection. It is so closely combined, 

 that it does not rapidly decompose. Buildings of granite will 

 last for ages in dry climates, but a piece put into the soil where 

 vegetation is active over it, will speedily lose weight. 



I have alluded before to this wonderful dissolving power in 

 the roots of growing plants. A carious illustration of this 

 74 



