488 



We were sometimes lost in the mist, and 

 could not without difficulty find our way. At 

 this height there is no path, and we were obliged 

 to climb with our hands, when our feet failed 

 us, on this steep and slippery acclivity. A vein* 

 filled with porcelain clay attracted our atten- 

 tion. It is of a snowy whiteness, and no doubt 

 the remains of a decomposed feldspar. I gave 

 considerable portions of it to the intendant of 

 the province. In a country where fuel is not 

 scarce, a mixture of refractory earths may be 

 useful, to improve the earthen ware, and even 

 the bricks. Every time the clouds surrounded 

 us, the thermometer sunk as low as 12°-f~ ; with 

 a serene sky it rose to 21°. These observa- 

 tions were made in the shade. But it is diffi- 

 cult on such rapid declivities, covered with a 

 dry, shining, yellow turf, to elude the effects 

 of radiant caloric. We were at nine hundred 

 and forty toises of elevation ; and yet at the 

 same height toward the east we perceived in a 

 ravin, not merely a few solitary palm-trees, but 



* The breadth of the vein is three feet, it's direction is 

 hor. 1*2 of the compass of Freyberg, while that of the gneiss 

 is every where hor. 3*4, with 50° or 60o of dip to the north- 

 west. This porcelain clay, when moistened, readily absorbs 

 the oxygen of the atmosphere. I found, at Caraccas, the 

 residual nitrogen very slightly mingled with carbonic acid, 

 though the experiment was made in phials wjth ground glass 

 stopples, not filled with water, 



t To 9*6° R. 



