ELECTRICAL EXPERIMENTS* \$ 



very "brilliant spark ramified upon its surface ; but if these 

 ramifications be minutely examined, they will be found to 

 proceed from the conductor, and running up the sides of 

 the crystal converge to a point under the knob of the dis- 

 charger. 



Whenever it is doubtful whether a crystal affords a spark Remedies, &t. 

 or not, I place a second crystal upon the first, and then ap- 

 ply the discharger to the uppermost, when in general, 

 merely a hissing stream of electric light, or at most, a small 

 hissing spark is perceived. Again, if the crystal be thin, 

 it will appear to give as good a spark as any metal, and in 

 truth the spark really proceeds from the conductor, and 

 passing through the salt renders it transparent, or rather 

 semi-transparent. A thin cake of agglutinated crystals al- 

 lows the spark to pass through its interstices with the same 

 appearance. It is necessary here to remark, with respect 

 to passing the shock through saline substances, that if the 

 salt be crystallized in large lumps like alum or borax, it is 

 shivered in pieces by the shock; and the same happens when 

 the lump consists of a congeries of regular crystals; but if 

 the shock (meaning the shock which I constantly employ in 

 these experiments, and which is never more than that from 

 a quart phial) be passed through a single crystal, no such 

 effect occurs, for the crystal remains perfectly whole, and is 

 generally rendered luminous throughout, should the salt 

 prove phosphoric by the electric light. 



Alkalies and their Compounds. 



Sub-carbonate of potash. 1st. Pearl ash gives a dense Alkali and al« 

 purple stream of electric light, instead of a spark, and is kal,ne sate- 

 extremely phosphoric by the shock, its light continuing some 

 minutes. 2nd. Salt of tartar is very luminous, and its par- 

 ticles are easily scattered by the shock, when the points of 

 the dischargers are in contact with it. 



Super-carbonate of potash in small crystals is luminous, 

 and scattered about, if the rods touch it; in larger crystal* 

 it is also luminous, but they are not fractured by passing 

 the shock through them.* 



* I am inclined to suspect that the shock does not pass through,, 

 but over the surface of a single crystal, if it be a small crystal. 



Sulphate. 



