124 Notice of some Mecent 



If the sky is calm, the signs of negative electricity dis- 

 appear in the interior of the wood, at the same time that 

 positive electricity is developed in the air. On three days, 

 when the sky was cloudy, and almost stormy, negative 

 electricity was detected in the external air, and in the 

 wood. Hence, it may be inferred, that negative electricity 

 is disengaged by vegetation during the day, which is con- 

 stantly neutralized by positive electricity. Matteuci has 

 promised to continue his observations, and expresses a 

 strong desire that similar investigations should be under- 

 taken by meteorologists in other parts of the world, especially 

 in reference to rain.* 



6. Nobili's paper, on the distribution and effects of electrical 

 currents in conducting masses, •); derives much interest from 

 the circumstance, that it constitutes the last literary work 

 of this active philosopher, who died in August last, aged 

 51, having been born in 1784. In this paper, he sets 

 out with investigating the distribution of currents, in 

 metallic conductors, in liquid conductors, and at the points 

 where the currents pass from one conductor to another. 

 He describes two modes of studying electric currents ; 1st, 

 By the galvanometer. This process consists in procuring a 

 small tube equally large and deep in all its extent, and 

 from one to two feet in length. It is placed horizontally, 

 and closed at each of its extremities by means of two 

 metallic plates of similiar dimensions to that of its orifices. 

 The plates are intended to introduce the electric current 

 into the canal, after the latter has been filled with mercury. 

 After the current has been introduced, the points of the 

 galvanometric explorer^ are brought to the surface of the 

 mercury. The galvanometer indicates a certain deviation, 

 12° for example. If the points are made to penetrate into 

 the interior of the mass, the deviation remains stationary. 

 Such is the method applicable to the first class of uniform 

 conductors. For conductors of the second class, we must 

 substitute acidulated, or saline water, for the mercury. 



* Bibliotheque Universellp, Ma}', 1835, 38. 



t lb. July and August, 1833, 263, 416. 



| This consists of two similar platinum points fixed in a piece of wood or cork, 

 in order that they may be kept at a proper distance from each other, and each 

 communicating with one of the extremities of a sensible galvanometer. 



