20 HISTORY OF GALVANISM. 



ceived by them to prove the electrical nature 

 of the phenomena in question, only went so far 

 as to show, that electricity was concerned in 

 the operation, but did not prove it to be the cause 

 of them ; and he is inclined to regard it rather as 

 the effect. 



Fabroni mentions, among other facts, that mer- 

 cury and tin when pure, and kept distinct from 

 other metals, will remain a long time without tar- 

 nishing ; but when alloyed, or placed in contact 

 with other metals, they soon begin to exhibit signs 

 of oxidation. He remarked, that coins composed of 

 a pure metal were more durable than such as 

 were composed of a mixture of metals. He men- 

 tions the corrosion which takes place, when cop- 

 per roofs are soldered with another metal, and in 

 the copper sheathing of ships when fastened with 

 iron nails. These phenomena are supposed to 

 depend upon a chemical affinity between the me- 

 tals, by which their particles are individually 

 attracted towards each other, while the separa- 

 tion of the particles of the solid metal, which is 

 caused by their tendency to unite, permits the 

 oxygen to act upon them. " These facts," he says, 

 " as well as many others of the same nature, no 

 less common than well known, ought to have 

 proved to philosophers, that the metals, by exer- 

 cising their mutual attractive force, must by 

 the same energy diminish their respective powers 

 of aggregation; that though neither of them 

 separately may be able to attract oxygen from the 



