452 The Rev. J. W. MacGauley on some remarJcable Results 



explained by the fact made known by Mr. Faraday, that air 

 when heated becomes a conductor. But that could not apply 

 here, lor in the first place, it is not air at all that is the me- 

 dium of conduction, it is liquid iodine; and in the second, on 

 melting the iodine and inverting the tube the conduction is 

 suspended. 



Dr. Apjohn now suggested that the iodine at the tempera- 

 ture required for its liquefaction might act on the platinum, 

 and that an ioduret of platinum thus formed would conduct. 



But iodine does not act on platinum at '225° Fahr., and 

 225° is the point at which iodine fuses. 



This I stated at the time the objection was made, and since 

 my return I have accurately weighed a piece of platinum wire, 

 and allowed iodine to act on it for half an hour, at and above 

 the point of fusion; when on weighing again, the platinum 

 wire was found to have lost nothing ; so that Dr. Apjohn's 

 objection thus loses its weight, no ioduret having been 

 formed. 



The conducting power of iodine, atmospheric air, and 

 some other substances when heated, and their non-conducting 

 when cold, adds, I think, an argument in favour of that theory 

 which considers electricity to be but an action of matter ; and 

 heat and electricity to be but modifications of each other. 



Castle Douglas, Oct. 3, 1836. James Inglis. 



LXXXIV. An Account mid Explatiation of some remarkable 

 Residts obtained during a Course of Electro- Magrietic Expe- 

 riments. By the Rev. J. W. MacGauley*. 

 IT is impossible not to remark that the electro-magnetic he- 

 -^ lix seems to increase the power of a given battery, for the 

 brilliancy of the spark increases with the magnitude of the ap- 

 paratus. I expected that such an intensity might be given by 

 a very powerful electro-magnet, as that a small galvanic ar- 

 rangement and a single circle might be made to communicate 

 a considerable shock. I coiled nearly 2000 feet of copper wire, 

 in ten helices, upon a bar of soft iron, during the experiments 

 I was making preparatory to the construction of a large arid 

 greatly improved machine on the principle which I exhibited 

 last year (1835) to the British Association, and which is now 

 nearly completed : from this magnet I obtained a powerful 

 shock. 



It is not necessary to detail a great variety of arrangements 

 adopted and results obtained ; among others I came to the fol- 

 lowing conclusions: 



* Read before the Royal Dublin Society on June 14th; and now coni- 

 munji-ated by the Author. 



