the Decomposition of the Earths, &c. 197 



A mixture of two-thirds of barytes and one-third of oxide 

 of silver very slightly moistened was electrified by iron wires j 

 an effervescence took place at both points of contact, and a 

 minute quantity of a substance, possessing the whiteness of 

 silver, formed at the negative point. When the iron wkcto 

 which this substance adhered was plunged into water con- 

 taining a little alum in solution, gas was disengaged, which 

 proved to be hydrogen ; and white clouds which were found 

 to be sulphate of barytes, descended from the point of the 

 wire. 



A mixture of barvtes and red oxide of mercury, in the 

 same proportions, was electrified in the same manner. A 

 6mall mass of solid amalgam adhered to the negative wire, 

 which evidently contained a substance, that produced barytes 

 by exposure to air, with the absorption of oxygen ; and which 

 occasioned the evolution of hydrogen from water, leaving 

 pure mercury, and producing a solution of barytes. 



Mixtures of lime, strumites, magnesia, and red oxide of 

 mercury, treated in the same manner, gave similar amal- 

 gams, from which the alkaline earths were regenerated by 

 the action of air or water, with like phenomena ; but the 

 quantities of metallic substances obtained were exceedingly 

 minute; they appeared as mere superficial formations sur- 

 rounding the point of the wire, nor did they increase after 

 the first few minutes of electrization, even when the process 

 was carried on for some hours. 



These experiments were made previous to April, 1808, at 

 which time the batteries were so much injured by constant 

 use, as no longer to form an efficient combination. The in- 

 quiry was suspended for a short time : but in May I was 

 enabled to resume it, by employing a new and much more 

 powerful combination, constructed in the laboratory of the 

 Royal Institution, and consisting of five hundred pairs of 

 double plates of six inches square. 



When I attempted to obtain amalgams with this appa- 

 ratus, the transmitting wires being of platina, of about Vo-th. 

 of an inch in diameter; the heat generated was so great as 

 to burn both the mercury and basis of the amalgam at the 

 moment of its formation; and when by extending the sur- 



N 3 faces 



