102 



Sulphuret of 

 barytes. 



Mliriatic 

 £cnus. 



Mica gives 

 sparks. 



ELECtRIC tlGHT: 



place in the calcareous genus, in whicli the carbonates gire 

 sparks, though they are slightly luminous, compared to the 

 sulphates, which are brilliantly phosphoric, but afford no 

 spark; whereas in the barytic genus the carbonates are 

 beautifully luminous, but give no sparks, while the sulphates 

 afford good sparks, but are slightly phosphorescent. 



Sulphuret of barytes was but slightly luminous by the 

 electric explosion ; in which it essentially differs from the 

 sulphuret of lime*, which is the most brilliant phosphorus, 

 both by the electric and solar light, that I have yet seen. 



Muriatic Genus. 



Magnesia, pure, and carbonated, were both luminous by 

 the electric explosion ; the li^ht, however, continued but for 

 a short time. 



Sulphate of Magnesia is very luminous through its whole 

 substance. 



Sulphuret of Magnesia is luminous, but not more so than 

 the carbonate. 



Turkey tobacco-pipes. — The bowls of these articles af- 

 forded tolerable sparks, but were scarcely luminous, except 

 in the track of the electric fluid, when the points of the 

 discharging rods rested upon the surface. 



Chlorite gave sparks, which, upon its surface, branched 

 off in minute, different-coloured points, something similar to, 

 though not so brilliant as, the spark taken from any lac. 

 quered substance, such as gilt leather, or lacquered Avooden 

 ornaments. The explosion rendered it luminous. 



Steatites, Talc, and fibrous Amianthus, gave sparks, and 

 were slightly luminous by the explosion. 



Asbestus. — A thin polished slab of this stone gave sparks 

 similar to Chlorite, but the ramifications upon its surface 

 were more numerous, and more variegated. 



Mica affords sparks, but I could not observe it luminous 

 by the explosion, When held in the hand it allows the 

 sparks to run along its surface, to strike the finger at a con-r 



* Canton's phosphorus is so readily Illuminated by electricity, that 

 a large lump, newly made, partaking of the exact shape of the cru- 

 cible, and having never been exposed to light, being placed upon the 

 prime conductor, was beautifully bespangled with brilliant spots, 

 merely by taking the spark from various parts of its surface. 



siderablo 



