172 Mr. J. Goodman's Researches on Electricity. 



tion of such bodies, and may thus afford an interesting illus- 

 tration of the connexion which exists between different branches 

 of jDhysical science. In my Treatise on the Heat of Vapours, 

 p. -iS, I have given a table, showing, upon the hypothesis I 

 there adopted, the density and temperature for a given height 

 above the earth's surface. According to that hypothesis, at 

 a height of fifteen miles the temperature is 24-0°*6 F. below 

 zero, the density is '03573, and the atmosphere ceases alto- 

 gether at a height of 22"35 miles. In the Comptes Renchis ties 

 Seances de V Academic des Sciences, tom. viii. p. 95, M. Biot 

 has verified a calculation of Lambert, who found from the 

 phaenomena of twilight the altitude of the atmosphere to be 

 about eighteen miles. The constitution of the higher regions 

 of the atmosphere, according to the hypothesis adopted by 

 Ivory, is very different, and extends to a much greater height. 

 See p. 3 of the Supplement to my Ti-eatise on the Heat of 

 Vapours, where I have given a table showing the constitution 

 of the atmosphere according to Ivory. Such a table for the 

 constitution due to Laplace's hypothesis is still wanted. 



XXVIII. Researches into the Identity of the Existencies or 

 Forces — Lights Heat, Electricity a7id Magiietism. By 

 John Goodman, Esq.* 



On Thermo-Electricity. 



IT was discovered some years ago by Mr. Sturgeon, that 

 thermo-electricity does not require more than one metal 

 for its development. 



In confirming this discovery, I have found that the current 

 was developed only by the more crystalline metals, bismuth, 

 antimony, iron, steel, zinc^ &c., as will appear on inspecting 

 the accompanying table. 



I found also that each metal possessed its own distinctive 

 and peculiar amount of current, as indicated by the galvano- 

 meter, and that always in the same direction: that when two 

 opposing metals were united in producing a thermo-current, 

 the minor current would be found to neutralize the opposing 

 current, precisely to the amount of its own powers, and with 

 as much exactitude as if it had been done by arithmetical 

 calculation. 



Thus iron alone gave 7|° current. Conjoined with zinc 5°; 

 zinc alone 2\° in the opposite direction. 



It was also discovered that a minor current conjoined to one 



* From vol. viii. of the Manchester Literary and Philosophical Society's 

 Memoirs, and communicatsd by the Author. 



