of Devonshire and Cornwall. 135 



Thus we find, that all those rocks which are geologically arranged 

 with serpentine, contain in greater or less proportion, several sub- 

 stances quite foreign to it, and what is still less satisfactory, we find 

 that the same rocks analysed by different chemists, frequently give 

 very different results. I believe that upon full examination, we shall 

 agree with the observation of Saussure, that substances of very dissi- 

 milar natures are often included in rocks which do not at all, or very 

 slightly resemble them, although both may have been formed 

 simultaneously ; but that, in consequence of certain principles of 

 affinity, the simila" particles of the different materials suspended in 

 the fluid, united and formed distinct rocks.* 



In considering the steatite, a mineral which still more frequently 

 than the diallage and jade accompanies the serpentine, I shall adopt 

 the same method I have pursued in treating of these last substances. 



Steatite is found not only intimately combined with serpentine, 

 but frequently in masses forming subordinate beds in that rock '^ 

 such are the soap-rocks at the Lizard. 



There is in the valley of Sesia Grande, about half a league to the 

 north of Alagna, and consequently, at the foot of Mount Rosa, a bed 

 of true potstone in the serpentine. It is so soft as to be worked upon 

 the lathe j and dishes are made of it which are known in the country 

 by the name oi lave%%i.-\ But I learned upon the spot, in 1806, 

 that they had given over w^orking the quarry, since it had been en- 

 cumbered by the fall of an enormous block of serpentine. In the 

 mountains of Chiavenna, and also in the valley of Chamouni, steatite, 

 in scattered blocks is often met with, though, according to the ob- 

 servation of Saussure, less frequently on the side of the Alps than on 

 the side of Italy.:]: 



Estner suspects, that the beilstein (a variety of steatite) must form 



* Voyages dans Ics Alpcs, § 1312. + Voyages dans Jes Alpes,^ 2151. +Ibid. § 716.. 



