302 Mineralogical Journey. 



warm ashes, I found, as might have been expected, it attracted the 

 metallic needle, on bringing it near one of the little knobs by which it 

 is terminated. Five or six hours afterwards, having occasion to ex- 

 plain this action to a friend, I had brought the Rubellite no nearer 

 than three quarters of an inch of one of the balls, when it began to 

 approach ; and such was the force of the attraction, that the impetus 

 acquired by the needle in coming up to the broach was sufficient to 

 give it, very nearly, a complete revolution. This experiment we re- 

 peated a number of times, without observing any diminution in the 

 attracting force. The broach had been laid aside, in an apartment 

 without fire, and during the experiment was attached to a card, to 

 avoid the warmth of the hand. The same phenomenon took place 

 the succeding morning, though with less activity ; and I have scarce- 

 ly ever had occasion to repeat the experiment since, (notwithstanding 

 the weather has not been warmer than 75°,) without observing the 

 same effect. Whenever I have desired to render the excitement 

 more energetic, it has only been necessary to place the thumb upon 

 it for half a minute, or to hold it in the rays of the sun for a little 

 while. The other polished Tourmalines do not appear equally sensi- 

 ble to electrical excitement, although the warmth of the finger, or the 

 sun's rays, are always sufficient to put the needle in motion. 



The specific gravity of the transparent Rubellite is 3.021 ; that of 

 the green Tourmaline 3.009; and that of the Indicolite 3.055. 



The Rubellite, on being heated to redness before the blow-pipe, 

 loses its color; and on increasing the heat, whitens, becomes opake 

 and swells, at the same time opening by numerous little fissures. 

 Examined in this condition by the microscope, it evinces a partial 

 vitrification and a rounding of the extreme points. With borax, it 

 dissolves readily with effervescence, into a glass of a deep rose color, 

 and with soda, into an opake glass of a green color, with a shade of 

 blue, — the color being discharged on being brought within the inner 

 flame of the blowpipe. The green Tourmaline grows pale on being 

 heated to redness, and on continuing the heat, it becomes milk white, 

 swells, cracks, and vitrifies with less appearances of fusion than the 

 Rubellite. With borax, it dissolves, — producing a transparent glass 

 with a slight tinge of iron. The Indicolite retains its color perfectly, 

 when heated to a low redness ; in a higher heat, it swells slightly, 

 turns of a yellowish gray, vitrifies and undergoes a partial fusion at its 

 angles. With borax it dissolves easily, and presents a pale green 

 transparent glass. With salt of phosphorus, it dissolves, leaving a 



