]Q6 KLECXaiCAL EFFECTS FRODUCED BY FRICTION. 



little now remaining in my possession. Its taste is the same as 

 of that obtaitied in the first experiment ; viz. a bitter aromatic, 

 uniting the flavour of hops with that of nutmegs. I have re- 

 marked, that the flame arising from its combustion is edged 

 with green. 

 Compound of Still more recently, viz. on the 15th of January last, I ob- 

 •ulphur. ^" tained a compound of this fluid with sulphur, by acting on oil of 

 turpentine by Dr. Thompson's sulphuretted liquid, or sulphu- 

 rane. This compound is decomposed by solution of potassa, 

 which dissolves the sulphur, and separates the peculiar fluid, 

 which then exhibits, as far as I have been able to judge, all the 

 characters of that formed by the direct combination of chlorine 

 with oil of turpentine. This experiment, I recollect, appeared 

 to me, at the time that I made it, as very favourable to the 

 opinion formed by Sir Humphrey Davy of the nature of Dr. 

 Thompson's sulphuretted liquid. 

 Whether this I cannot positively say whether the peculiar fluid formed in 



peculiar fluid jj^g j{j,.gg experiments just described is identical with that 

 be the same as r j 



that of Mr. produced by Mr. John Davy from the mutual action of stan- 

 JohnDavy. nanea and oil of turpentine. Reasoning from analogy would 

 induce me to conclude that it is ; but some diflcrences in our 

 descriptions of those fluids oblige me to suspend forming a de- 

 cided opinion, until the fluids themselves have been compared. 

 I am. Sir, 

 Your most obedient Servant, 



R. PORRETT, JuN. 



VI. 



On ihe Electrical Effects produced by Friction between Bodies, In 

 a Letter from J. A. De Lue, Esq. F. R. S. 



To William Nicholson, Esq. 

 SIR, 



IN my former papers I have communicated to you my re- 

 »v^.^.v..v.v. .., marks on Dr. Maycock's electrical system; and I come 



former papers. jiQW to his paper in your Journal, No. 144, concerning th» 

 production of electrical excitement by friction. This paper con- 

 cludes by the following very judicious remark, which induces 

 me-to offer here to him my ideas on the same subject. 



"It 



