108 



Monday^ 4:th January 1836. 



Sir THOMAS M. BRISBANE, President, in the Chair. 



The following Donations were presented : — 



Memoires de la Societe Geologique de France. Tome i. part 1. 

 Bulletin de la Societe Geologique de France. Tome vi. Feuilles 



5-20. — By the Society, 

 Nouvelles Annales du Museum d'Histoire Naturelle. Tome iv. 



Liv. 2 and 3. — Par les Editeurs. 



The following Communications were read : — 

 1. Some Observations on Atmospherical Electricity. By Dr 

 John Davy, F. R. S. Communicated by Professor For- 

 bes. 



This paper, tending to establish the chemical action of atmospherical 

 electricity, is based upon experiments made in Malta between Ol 

 ber 1834 and March 1835. The mode of operating was the folio 

 ing : A tube of glass containing a wire of copper was elevated six 

 feet in all above a turret in Dr Davy's house in Valletta, which rose 

 just fifty feet from the street. It was not in the highest part of the 

 town, and was overtopped by other buildings. "To the lower part 

 of the copper- wire was attached one of gold. The communication 

 to the ground was effected through the medium of anothercopper- 

 wire, connected with a leaden cistern. Between these two por- 

 tions of the line of communication from the sky to the ground was 

 interposed the decomposing apparatus, consisting of a tube contain- 

 ing iodide of potassium mixed with starch, and into which two pla- 

 tinum wires were inserted, until within one-fourth inch of being in 

 contact. It was found that, with this arrangement, decomposition 

 was generally going forward even in fine weather, — that it in- 

 creased in windy or cloudy weather, and especially during the con- 

 tinuance of the sirocco or S. E. wind. During thunder storms, 

 showers of hail, and also of rain, the effect was notably increased. 

 A deposition of iodine was frequently observed on both wires, 

 which Dr Davy attributes to successive changes in the electrical 

 state of the passing clouds. Dr Davy was only once able to ob- 

 tain distinct indications of the decomposition of water ; in that case 

 a strong solution of salt was employed, and fine sewing needles 

 coated with sealing-wax, except at the points, were used as con- 



