“All bodies conduct electricity in the same manner from metals to lacs and gases, but in very different degrees.
“Conducting power is in some bodies powerfully increased by heat, and in others diminished, yet without one perceiving any accompanying essential electrical difference, either in the bodies, or in the change occasioned by the electricity conducted.
“A numerous class of bodies insulating electricity of low intensity, when solid, conduct it very freely when fluid, and are then decomposed by it.
“But there are many fluid bodies which do not sensibly conduct electricity of this low intensity; there are some which conduct it and are not decomposed; nor is fluidity essential to decomposition.
“There are but two bodies (sulphuret of silver and fluoride of lead) which, insulating a voltaic current when solid, and conducting it when fluid, are not decomposed in the latter case.
“There is no strict electrical distinction of conduction which can as yet be drawn between bodies supposed to be elementary, and those known to be compounds.”
[138] Faraday’s Speculation on the Nature of Matter, already referred to.
[139] Experimental Researches: by Dr. Faraday. Chemical Decomposition, p. 151.
[140] Karsten; Poggendorff’s Annalen, vol. lvii.
[141] Traité Expérimental de l’Électricité et du Magnétisme: Becquerel, 1834, Priestley’s Introduction to Electricity. On Electricity in Equilibrium: Dr. Young’s Lectures.