Intelligence and Miscellaneous Articles. 79 



of combining, as he expected, at the negative pole, separated, the 

 lead being deposited in the form of oxide upon the positive, and the 

 copper in a metallic state on the negative plate. 



The decomposition was eflected by two of Buusen's elements ; the 

 acetates of copper and lead were mixed in atomic proportions and 

 dissolved in seven to eight parts of water. As soon as the circuit 

 is closed, the positive (charcoal) platinum plate is seen to acquire 

 a reddish-brown tint. In eight or ten hours the positive plate is 

 covered with a coat resembling a black varnish, and if the experiment 

 be continued still longer, the deposit becomes detached from certain 

 points and falls to the bottom of the vessel, or rises to the surface 

 by means of the adherent gas. 



The deposit on the negative pole is red copper mixed with traces 

 of lead. This copper dissolves rapidly at the ordinary temperature 

 in pure nitric acid of spec. grav. r329, or diluted with water. The 

 black deposit of the positive pole only dissolves in small quantity in 

 such nitric acid at a boiling heat, even by several days of contact. 

 On the addition of muriatic acid the action is brisk, and the black 

 substance is changed into white chloride of lead. This chloride, 

 treated with an excess of nitric acid, is converted into nitrate. 



The black substance heated by the spirit-lamp in a glass tube, 

 acquires the red colour of bichromate of potash without losing its 

 lamellar form. In this state it gives a brick-red powder, which, 

 treated with nitric acid, is partially dissolved ; the residue is black. 

 Some other experiments lead to the belief that the black matter is 

 binoxide of lead. 



From some experiments made to determine whether the presence 

 of copper in the mixture is necessary for the formation of this black 

 coat, it appears that nitrate of lead, and the jjure or commercial 

 acetate, furnish the same black matter at the positive pole and 

 metallic lead at the negative pole, and that with a mixture of the 

 acetates of lead and cadmium, the same black substance is always 

 found at the positive pole, and lead mixed with cadmium at 

 the negative. Protacetate of manganese gave no deposit on the 

 negative pole, and deposited a black, oxidized compound on the 

 positive pole. The absence of deposit at the negative pole is pro- 

 bably due to the metal being dissolved by the free acid as fast as it 

 is deposited. The black deposit on the positive pole is not man- 

 ganese, or protoxide of manganese, or manganic acid ; it is unalter- 

 able in aiirated water and insoluble in nitric acid. At the ordinary 

 temperature it dissolves in dilute sulphuric acid. The solution is 

 red. 



In tartrate of potash and antimony the negative plate is covered 

 with crystalline metallic antimony, and the positive plate with a 

 yellowish-red coat. In the course of a few days the yellow pre- 

 dominates. After immersion for eight days in distilled water, it is 

 perfectly yellow. It is probably aniiydrous antiiuonic acid. The 

 author proposes making experiments with other metals to see whether 

 a similar separation takes place in them. 



