“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. [142] Faraday’s _Experimental Researches on Electricity_. This philosopher has shown, by the most conclusive experiments, “that the electricity which decomposes, and that which is evolved by the decomposition of, a certain quantity of matter, are alike. What an enormous quantity of electricity, therefore, is required for the decomposition of a single grain of water! We have already seen that it must be in quantity sufficient to sustain a platinum wire 1/104 of an inch in thickness, red hot, in contact with the air, for three minutes and three quarters. It would appear that 800,000 charges of a Leyden battery, charged by thirty turns of a very large and powerful plate machine, in full action--a quantity sufficient, if passed at once through the head of a rat or cat, to have killed it as by a flash of lightning--are necessary to supply electricity sufficient to decompose a single grain of water; or, if I am right, to equal the quantity of electricity which is naturally associated with the elements of that grain of water, endowing them with their mutual chemical affinity.” [143] _Experimental Researches_: Faraday.