450 Royal Society, 



F.R.S., Fullerian Professor of Chemistry in the Royal Institution of 

 Great Britain. 



The author, while prosecuting his researches on electro-chemical 

 decomposition, observed some phenomena which appeared to be refer- 

 able to a general law of electric conduction not hitherto recognised. 

 He found that an electric current from a voltaic battery, which is 

 readily conducted by water, did not pass through ice : even the 

 thinnest rilm of ice, interposed in the circuit, was sufficient to inter- 

 cept all electric influence of such low intensities as that produced by 

 the voltaic apparatus, although it allows of the transmission of elec- 

 tricity of such high intensity as that excited by the common electrical 

 machine. The author ascertained that a great number of other sub- 

 stances, which are solid at ordinary temperatures, do not conduct the 

 electric current from the voltaic battery until they are liquefied. 

 Among these are potassa, protoxide of lead, glass of antimony, and 

 oxide of bismuth ; various chlorides, iodides, and sulphurets ; and 

 also many of the ordinary neutral salts with alkaline bases. In almost 

 every instance the bodies subjected to this law are decomposable by 

 electricity j and their decomposition can be effected only when they 

 are in a fluid state, and while they are conductors of electricity. The 

 author inquires how far these two properties are connected together, 

 or dependent the one upon the other ; but finds that several excep- 

 tions occur to any general proposition that he attempted to establish 

 on this subject. 



The general conclusions to which he is led from the experiments 

 detailed in this paper are the following : — First, that all bodies con- 

 duct electricity in the same manner, but in very different degrees; — 

 Secondly, that in some the conducting power is powerfully increased 

 by heat, in others diminished, and this without any difference that 

 has yet been discovered, either in the general nature of the substance, 

 or of the influence of electricity upon it ; — Thirdly, that there is a 

 numerous class of bodies which, when solid, insulate electricity, and, 

 when fluid, conduct it freely, and are decomposed by it ; yet that 

 there are many fluid bodies which do not sensibly conduct electricity 

 of low intensity 5 and some that conduct it, and are not decomposed j 

 — and, Lastly, that fluidity is not essential to decomposition. Sul- 

 phuret of silver is the only body yet known to be capable of insu- 

 lating a voltaic current when solid, and of conducting it, without de- 

 composition, when fluid. No distinction can as yet be drawn between 

 the conducting powers of bodies supposed to be elementary and those 

 known to be compounds. 



The Society then adjourned over Whitsun-week to the 6th of June. 



June 6*. — A paper was read, entitled, " An Account of a Second 

 Series of Experiments on the Resistance of Fluids to Bodies passing 

 through them." By James Walker, Esq., F.R.S., Civil Engineer. 



The author, in a paper read to the Society in the year 1827, and 

 printed in the Philosophical Transactions, gave an account of some 

 experiments showing that the resistance of fluids increases in a ratio 

 considerably higher than the square of the velocity, and that the ab- 

 solute resistance is smaller than had been deduced from the experi- 



