ELECTRICAL EXPERIMENTS. *17 



salt are placed in the track of the discharge between the Metallic salts, 

 points of the rods it explodes with a slight shock. The ex- 

 plosion is accompanied with a dark red or crimson coloured 

 flame and slight detonation. It is a very pleasing experi- 

 ment, and when exploded upon a plate of glass the mercury 

 is revived, and silvers the plate like a mirror, but it is easily 

 effaced. When exploded upon card, a coloured stain is pro. 

 duced, which is indelible. 



Muriate of mercury, called calomel, is not luminous. 



Oxymuriate of mercury, or corrosive sublimate of mer~ 

 cury, affords only a purple stream on its fracture, but the 

 smooth convex surface, which has formerly been attached to 

 the vessel it was sublimed in gives a fine purple spark, of a 

 beautiful bright green colour on its surface. It is very phos- 

 phorescent by passing the shock above it. Great caution is 

 required in making experiments with this substance, as elec- 

 tricity detaches from it, and throws into the atmosphere, 

 innumerable minute and invisible particles of this caustic 

 poisonous salt, which produce inflammation of the mem- 

 brane lining the nose, and a very disagreeable sensation in 

 the mouth and fauces, attended with a slight salivation.— 

 Similar effects occur during the explosion of the fulminating 

 mercury, if frequently repeated. 



Sulphate, nitrate, and phosphate of copper are not lu- 

 minous, neither do they give any spark. 



Acetite of copper, verdigris of the shops, gives a spark 

 ramified upon jits surface, but is not luminous by the electric 

 explosion. 



Carbonate or rust of iron gives a spark, but is not lu- 

 minous. 



Sulphate, gallate, and prussiate of iron are not luminous. 



Carbonate and acetite of lead give no spark, nor are they 

 luminous. 



Muriate of lead is slightly luminous by the explosion. 



Sulphate of zinc affords a small purple stream instead of 

 a spark. It is not luminous when the explosion is made 

 fibove its surface, but merely in the track of the fluid when 

 the rods rest upon it, at some distance from each other. 



Carbonate of zinc or calamine. Several native specimens 

 Vol. XVII.— June, 1807. Q 9 t 



