464 Colour oftheSodalite. — Aeronautic Ascent. 



dex of ordinary Refraction nearly 1*601. Colour grayish- white 

 lustre pearly upon /, vitreous in other directions. Transpa- 

 rent, translucent- 

 Hardness 2-5 . . . 3*0. Specific gravity = 2*76 of a perfect 

 crystal. Phosphorescence and Electricity, none by heat. 



This mineral resembles very strongly anhydrite and cryo- 

 lite, being two species of the order Haloide of Mohs. It is 

 soluble in acids without effervescence. According to an ex- 

 amination by the help of the blowpipe, instituted by M. Nor- 

 denskiold of Abo, it consists of some of the stronger acids, like 

 the phosphoric or boracic acid, mixed with zinc, some earthy 

 base, and cadmium. Hopeite occurs sparingly in the cavities of 

 several ores of zinc, found at Altenberg, near Aix-la- Chapel le. 

 This interesting substance has been established into a species 

 by Dr. Brewster, who named it in honour of Dr. Hope. — 

 Edin. Phil. T?a?is. vol. x. Part I. 



EFFECT OF LIGHT ON THE COLOUR OF THE SODALITE FROM 

 GREENLAND. 



Mr. Allan observed a very interesting phenomenon in rela- 

 tion to the action of light upon the colour of the sodalite of 

 Greenland. When the massive variety is broken up, many 

 portions of it have the most brilliant pink colour ; but after 

 a day's exposure to the action of light this brilliant pink co- 

 lour almost entirely vanishes. Having broken a specimen 

 into two, Mr. Allan kept one of them in the dark, and ex- 

 posed the other to light. The specimen kept in the dark re- 

 tained its pink colour unimpaired, while the other lost it al- 

 most entirely. — Brewster's new Journal, vol. i. p. 181. 



AERONAUTIC ASCENT. 



The following authentic particulars of the ascent of Mr. 

 Graham and Captain Beaufoy, from Islington, on Thursday, 

 the 17th of June, 1824, are extracted from "The Nation" 

 evening paper. 



The uncertainty of the weather in the morning prevented 

 Mr. Graham's ascending at so early an hour as had been in- 

 tended. 



A stage about five feet high was erected, on which all the 

 operations were carried on ; so that the spectators had an op- 

 portunity of viewing the whole of the balloon and car, with- 

 out inconvenience ; while the absence of poles or other 

 scaffolding secured the machine itself from any accidents. 



A number of assistants stood around, to hold down the 

 netting and half a dozen cords fastened to the top, gradually 

 giving way to the inclination of the balloon to rise, as it filled 



with 



