M. Becquerel on the Electric effects of Contact, fyc. 305 



Kapapula, and the next time he came by, the ground had 

 fallen in, forming the hollow that we saw, which also appear- 

 ed full of fissures. About three weeks ago, he saw a small 

 flame issuing from the apertures, and a quantity of smoking 

 lava all around. The branches of the trees that stood near 

 were also broken and burnt, and several of them still smoking. 



Though the surface of the whole country around had a 

 volcanic origin, this infant volcano seems to have i-emained un- 

 disturbed a number of years, perhaps ages. The lava is de- 

 composed, frequently a foot in depth, and is mingled with a 

 prolific soil, fertile in vegetation, and profitable to its proprie- 

 tors ; and we felt a sort of melancholy interest in witnessing 

 the first exhibitions of returning action, after so long a repose 

 in this mighty agent, whose irresistible energies will probably, 

 at no very remote period, spread desolation over a district now 

 smiling in verdure, repaying the toils, and gladdening the 

 heart of the industrious cultivator. 



Ponohohoa is situated in the district of Kapapula, and is 

 about ten or twelve miles from the sea-shore, and about twen- 

 ty miles from the great volcano at the foot of Mauno-roa. 



Art. XX. — Remarks on the Electric effects of' Contact pro- 

 duced by changes of Temperature. By M. Becqtjerel.* 



I his interesting paper, of which we propose to give an ab- 

 sti*act, is divided into three sections.-f- 



1. On the process for measuring the intensity of the electric 

 current. 



2. On the laws of the electric effects of contact when the 

 temperature of each metal is made to vary equally. 



I. The electro-chemical theory, as adopted by several cele- 

 brated chemists, admits it as a certain fact, that two bodies, 

 capable of combining, have different electric states when they 

 are put in contact ; that bodies which have an acid tendency 

 assume negative electricty, and alkaline ones the positive elec- 

 tricty ; that these electric states increase with the elevation of 



* Ann. de Chim, Avril 1826, torn, xxxi, p. 371. 



t See the next Article, which forms the third section. 



