EULOGY OX ALEXANDER YOLTA. 117 



This fact gave rise to the iiiterestin^i;- lesearches of .Spinas, Wilcke, 

 Cigna, aud Beccaria. Yolta also made it the subject of special study and 

 found in it the germ of the perpetual eleetrophorus, a wonderful instru- 

 ment, Avhich, however small, affords an inexhaustible supply of elec- 

 tricity, and which, without the necessity of resorting to friction of any 

 kind, aud whatever may be the state of the atmosphere, enables the 

 physicist to command incessant charges of undiminished power. 



The essay on the electrophorus was succeeded in 1778 by another 

 very important production. It was known even at this time that a 

 given body, hollow or solid, has the same electrical capacity, provided 

 the surface remains the same. An observation by Lemonnier pointed 

 out, moreover, that, besides equality of surface, the shape of the body 

 is not without its influence. Yolta was the first, however, to estab- 

 lish this principle on a solid basis. His experiments proved that of two 

 cylinders having the same surface, the longer receives the larger charge, 

 so that wherever the situation i^ermits, it is an immense ad\'antage to 

 substitute for the large conductors of ordinary machines a system of 

 very small cylinders, the total capacity of which is, however, not 

 larger than the other. By combining, for example, sixteen rows of 

 slender silver-plated rods, 1,000 feet in length each, a battery would be 

 formed, according to Yolta, capable of killing the largest animal. 



Not one of the discoveries of the professor of Como was the result of 

 accident. All the instruments with which he enriched science, before 

 being formed by the mechanic, were thoroughly planned in his mind. 

 There was no chance, for instance, in the changes made by Yolta in the 

 electrophorus in order to transform it into a condenser, a genuine micro- 

 scope of a new kind which detects the presence of electricity where 

 every other means would fail. 



In 177G and 1777, Yolta devoted himself for some months to a subject 

 of pure chemistry, in which, however, electricity, his favorite science, 

 was involved in the most fortunate combinations. 



At this epoch, chemists having as yet only discovered natural inflam- 

 mable gas in coal mines and mineral salts, regarded it as belonging 

 exclusively to mineral regions. Yolta, whose attention had been di- 

 rected to this subject by an accidental observation of P. Campi, showed 

 they were mistaken, lie proved that the putrefaction of both aninuil 

 and vegetable matter is always accompanied by the production of in- 

 flammable gas; that if stagnant water and the slime of a marsh be 

 stirred up, this gas will escape through the liquid, presenting the ap- 

 pearance of ordinary ebullition. Thus, the inflammable gas of marshes, 

 which for several years so much occupied the attention of chemists, is, 

 as to its origin, a discovery of Yolta. 



This discovery might lead to the belief that certain natural phenom- 

 ena, such, for example, as burning marshes and burning sjirings, arose 

 from a similar cause ; but Yolta knew too well how nature sports with 

 cur feeble understandings to be satisfled with mere analogy. In 1780 



