VARIOUS. 193 



in the day, I went to sleep at Courmayeur, dis- 

 tant from it two leagues, and returned on the 

 morrow. 



<c Quitting the bottom of the valley, you must 

 ascend for nearly three quarters of an hour, to 

 arrive where the schisti touch the granite. These 

 schisti, which at a distance only appeared a thin 

 surface, adhering against the foot of the moun- 

 tain, are a considerable mass of different layers. 

 The substance which composes the greater part 

 of these layers is remarkable, in that it briskly 

 effervesces with acids, and yet very easily melts 

 with the blow-pipe into a clear green transparent 

 glass j which runs and sinks on the tube of glass 

 to which it has been fixed. 



" Its colour is blackish, and its grain resem- 

 bles that of a limestone; I wished to see what 

 was the quantity of free absorbent earth that this 

 rock contained: I pulverised 100 grains of it, 

 which I pounded for an hour in distilled vinegar $ 

 this acid dissolved the half of it, and those 50 

 grains were found composed of 44 grains of lime 

 and 6 of magnesia. The other 50 grains which 

 had refused to dissolve in the vinegar, were 

 placed in decoction in aqua regis; being dis- 

 solved assisted by heat, 1?>47 grains of lime, 

 2,25 of argil, and 1,42 of iron, were extracted 

 from it, there remained 27 grains and a half of 

 \>OL. IT. o 



