£ 85 ] 



XV. The Bakerian Lecture for 1609. On some new Elec- 

 trochemical Researches on various Objects, particularly 

 the metallic Bodies, from the Alkalies, and Earths, 

 and on some Combinations of Hydrogen. By Iliw- 

 PHRYDAvr, Esq. Sec. U.S. F.R.S.E. W.R.LJ. 



[Concluded from p. 32.] 



IV. On the Metals of Earths. 



A have tried a number of experiments with the hopes of 

 gaining the same distinct evidences of the decomposition 

 of the common earths, as those afforded bv the electro- 

 chemical processes on the alkalies, and the alkaline earths. 



I find that when iron wire ignited to whiteness, by the 

 power of 1000 double plates, is negatively electrified and 

 fused in contact with either silex,alumine or glucinc, slightly 

 moistened and placed in hydrogen gas; the iron becomes 

 brittle and whiter, and affords bv solution in acids, an 

 earth of the same kind as that which has been employed 

 in the experiment. 



1 have passed potassium in vapour through each of these 

 earths, heated to whiteness in a platina tube : the results 

 were remarkable, and perhaps not unworthy of being fully 

 detailed. 



When silex was employed, being in the proportion of 

 about ten grains to four of potassium, no gas was evolved, 

 except the common air of the tube mingled with a little 

 inflammable gas, not more than might be referred to the 

 moisture in the crust of alkali, formed upon the potassium. 

 The potassium* was entirely destroyed; and glass with 

 excess of alkali was formed in the lower part of the tube ; 

 when this glass was powdered, it exhibited dark specks, 

 having a dull metallic character not unlike thatfof the pro- 

 toxide of iron. When the mixture was thrown into water, 

 there was onlv a very slight effervescence ; but on the ad- 

 dition of muriatic acid to the water, globules of gas were 

 slowly liberated, and the effect continued for nearly an 



* The results of this experiment are opposed to the idea that potassium 

 is a compound of hydrogen and potash or its basis ; for if so, it might be 

 expected that the hydrogen would be disengaged by the attraction of the 

 alkali for silex. In my first experiments on this combination, 1 operated 

 in an apparatus connected with water, and I found that the potassium 

 produced as much hydrogen as if it hud been made to act upon water; in 

 this case the metal had rapidly decomposed the Vapour of the water, which 

 must have been constantly supplied. 



F 3 hour ; 



