84 FARADAY 



action or electricity may be carried about. That strange 

 nugget of gold, of which there is a model in the other room, 

 and which has an interest of its own in the natural history 

 of gold, and which came from Ballarat, and was worth 

 8,000 or 9,000 when it was melted down last November, 

 was brought together in the bowels of the earth, perhaps 

 ages and ages ago, by some such power as this. And 

 there is also another beautiful result dependent upon chem- 

 ical affinity in that fine lead-tree ( a8 ), the lead growing 

 and growing by virtue of this power. The lead and the 

 zinc are combined together in a little voltaic arrangement 

 in a manner far more important than the powerful one 

 you see here, because in nature these minute actions are 

 going on forever, and are of great and wonderful im- 

 portance in the precipitation of metals and formation of 

 mineral veins, and so forth. These actions are not for a 

 limited time, like my battery here, but th?-y act forever in 

 small degrees, accumulating more and more of the results. 

 I have here given you all the illustrations that time will 

 permit me to show you of chemical affinity producing 

 electricity, and electricity again becoming chemical affinity. 

 Let that suffice for the present; and now let us go a little 

 deeper into the subject of this chemical force, or this elec- 

 tricity which shall I name first? the one producing the 

 other in a variety of ways. These forces are also won- 

 derful in their power of producing another of the forces 

 we have been considering, namely, that of magnetism; and 

 you know that it is only of late years, and long since I was 

 born, that the discovery of the relations of these two forces 

 of electricity and chemical affinity to produce magnetism 

 have become known. Philosophers had been suspecting this 

 affinity for a long time, and had long had great hopes of 

 success; for in the pursuit of science we first start with 

 hopes and expectations; these we realize and establish, 

 never again to be lost, and upon them we found new ex- 



Lead tree. To make a lead tree, pass a bundle of brass wires through 

 the cork of a bottle, and fasten a plate of zinc round them just as they 

 issue from the cork, so that the zinc may be in contact with every one of 

 the wires. Make the wires to diverge so as to form a sort of cone, and, 

 having filled the bottle quite full of a solution of sugar of lead, insert the 

 wires and cork, and seal it down, so as to perfectly exclude the air. I 

 a short time the metallic lead will begin to crystallize around the divergent 

 wires, and form a beautiful object. 



