278 



The inference drawn by Dr. Marcet from the general resemblance is, 

 that the river Jordan might possibly be the source of the saline in- 

 gredients of the Dead Sea, or that the same source of impregnation 

 might be common to both. 



The Bakerian Lecture, on some new Phenomena of chemical Changes 

 produced by Electricity, particularly the Decomposition of the fixed 

 Alkalies, and the Exhibition of the new substances which constitute 

 their bases ; and on the general Nature of alkaline Bodies. By 

 Humphry Davy, Esq. Sec. R.S. M.R.I.A. Read November 19, 

 1 807. [PAtY. Trans. 1 808, />.!.] 



In this lecture Mr. Davy, after recalling to our recollection the 

 series of experiments described in his last Bakerian lecture, in which 

 various bodies, consisting of known ingredients, having the highest 

 known affinities for each other, were decomposed by the agency of 

 electricity, reminds us also of a conjecture which he then formed, 

 that a greater intensity of the same power might likewise overcome 

 the affinities of other elements which had not hitherto been sepa- 

 rated, and proceeds to inform us that this conjecture is now fully 

 verified; for that by a laborious experimental application of the 

 powers of electro-chemical analysis, he has been enabled to decom- 

 pose various bodies which have appeared simple when examined by 

 common chemical means. 



Those of his experiments which are in the most mature state, re- 

 late to the decomposition of the fixed alkalies, and to the evolution 

 of new and extraordinary bodies which constitute their bases. 



His first attempts to effect the decomposition of these alkalies were 

 defeated by the presence of water, since on that occasion he employed 

 saturated solutions of them in water. 



In his second attempt, since solid dry potash is a perfect non-con- 

 ductor, he kept it in a state of fusion by intense heat, during elec- 

 trization by a voltaic battery, consisting of 100 6-inch plates, highly 

 charged. Under these circumstances the potash became a conductor; 

 and brilliant light, with an appearance of flame at the negative wire, 

 seemed to prove the development of combustible matter at this point 

 of contact ; but on account of the heat employed, no such product 

 could be collected. 



The method which he next pursued was more successful, as he 

 found that a very slight addition of moisture renders potash a con- 

 ductor, and that in this state it readily fuses by the electric power, 

 which at the same tune effects its decomposition. 



When a piece of potash, weighing as much as forty or fifty grains, 

 was exposed under these circumstances to the action of the battery, 

 consisting of 100 plates of six inches, with 150 of four inches in in- 

 tense activity, the potash began to fuse at both its points of electri- 

 zation. There was a violent effervescence at the upper, or positive 

 surface (by extrication of oxygen gas, as afterwards appeared), while 

 at the lower, or negative surface, there was no liberation of elastic 



