2 Biographical Sketch of Professor Volta, 



tallic and a resinous plate, by the successive contact of which 

 electricity may be perpetually developed. M. Wilcke had 

 made some considerable approaches to that invention, and con- 

 sequently the honour of it has been claimed for him by his 

 countr)'mcn ; but there can be no doubt that the electrophorus, 

 as an instrument, is an invention entirely new, and that its 

 eminent author was not even acquainted with the previous ex- 

 periments of the German philosopher. * 



During his summer vacations, he was in the habit of per- 

 forming journeys of considerable length. In 1777 he travel- 

 led through Switzerland, and, accompanied by his friend the 

 Count J. B. Giovio, he paid a visit to the celebrated Haller at 

 Berne, when that great man was sinking under the accumu- 

 lated infirmities of age and disease. They visited also Voltaire 

 at Ferney. 



In 1776 and 1777 Volta published some remarkable letters 

 on the inflammability of air disengaged from marshes. They 

 were addressed to Father C. J. Campi, and were afterwards 

 translated into French and German. In the same year he in- 

 vented his hydrogen lamp, and his electrical pistol, instruments 

 which are well known to all who have attended an experimental 

 course of chemistry and physics. The hydrogen lamp now 

 forms an elegant piece of furniture, in which a light can be at 

 all times obtained. A stream of hydrogen gas is made to issue 

 from a small aperture by means of the pressure of a column of 

 water, and the gas is kindled by a spark from an electrophorus 

 placed below. About the same time Volta discovered the eudio- 

 metrical process of determining the relative proportions of the 

 two gases, oxygen and azote, which compose atmospherical air. 

 A given measure of hydrogen gas being put into a glass tube 

 with a quantity of atmospheric air, it was inflamed by the 

 electric shock, and the quantity of oxygen was indicated by 

 the diminution of volume. 



During his travels in Tuscany in 1780 he studied with par- 

 ticular care the fires which burn among the Apennines, on the 

 road from Bologna to Florence, and which are known by the 



• See Wilcke, Disjmiatio Physica Experimentalis de Electricitatibus con" 

 irariis. Hosted, 1757 ; and Edinburgh Encyclopcedta, vol. viii. p. 423. 

 Art. Electricity. 



