266 Mr. Abraham on New Pkcenomena caused hy 



successful. The divers told me that there are other and infe- 

 rior strata of urao and mud alternating to a depth which they 

 could only reach by extraordinary exertions. The urao is 

 used by the natives to give pungency to their tobacco, by 

 steeping it in a solution. Smoking cigars thus prepared pro- 

 duces soreness of the mouth, really amounting to a slight sa- 

 livation. The inhabitants in the vicinity of the lake use a pre- 

 paration of this salt woi"ked into a paste, with tobacco, and 

 which they call chimo, carrying it in a small box slung round 

 the neck, and occasionally rubbing the nauseous mixture upon 

 the gums and tongue, — a practice which appears to be of In- 

 dian origin. According to the analysis of Boussingault, this 

 salt differs in no respect from that of natron. 



M. Palacio Faxar says (R. I. J. vol. vi. p. 192) that the 

 urao was analysed by Gay-Lussac, who found it to be natron 

 in no respect different from that found in the lakes of Egypt 

 and Fezzan. 



LV. Neta PlicEnomena caused by the Effect of Magnetic and 

 Electric Influence, and Siiggestionsfor ascertaining the Extent 

 of the Terrestrial Magnetic Atmosphere.* By J. H. Abra- 

 ham, F.L.S. 



To the Editor's of the Philosophical Magazine afid Annals of 

 Philosophy. 

 Gentlemen, 

 T^HE subject of this paper is, generally speaking, one that 

 -*■ has been till lately less understood than any other in na- 

 tural philosophy. 



It is a branch of science of which t have attempted to gain 

 some knowledge by numerous and often repeated experiments. 

 It is a branch of science so intricate in its laws and subtile in 

 its effects, that we can make but little progress in it without 

 experiment ; and as it is a subject which has of late excited 

 intense interest, it is presumed that the following observa- 

 tions and suggestions may not be deemed unworthy of in- 

 sertion in your valuable Journal. 



Active magnetism may be communicated to, or more cor- 

 rectly concentrated in, a bar of steel of any form, by rubbing 

 one of its sides only, and the power will be found to be equal 

 on any part of its surface at the same distance from the equa- 

 tor of the bar or magnet. 



* Communicated by the Author. Part of this paper has been read be- 

 fore the Royal Societ}-; and the whole was read before the Sheffield 

 Literary and Philosophical Society in August 1826. 



Magnetism, 



