Remarkable effects of Lightning observed in a Farm House. 71 



out producing any considerable elevation of its temperature ; not leaving 

 marks of combustion, if it be of an ordinary combustible material such 

 as wood. 



Dr. Robert Thomson, at my request, kindly undertook to examine the 

 paper removed from the wall of the farm-house, and enclosed with his 

 letter to me by Mr. Leitch ; so as, if possible, by the application of 

 chemical tests, to discover the staining substance deposited on its surface. 

 Mr. Leitch, in his letter, had suggested that it would be worth while to 

 try whether this case is an example of the deposition of sulphur which 

 Fusinieri believed he had discovered in similar circumstances. Accord- 

 ingly tests for sulphur were applied, but with entirely negative results. 

 Stains presenting a similar appearance had been sometimes observed on 

 paper in the neighbourhood of copper wires through which powerful dis- 

 charges in experiments with the hydro-electric machine had been passed ; 

 and from this it was suggested that the staining substance might have 

 come from the bell wires. Tests for copper were accordingly applied, and 

 the results were most satisfactory. The front of the paper was scraped 

 in different places, so as to remove some of the pigment in powder ; and 

 the powders from the stained, and from the not stained parts, were repeat- 

 edly examined. The presence of copper in the former was readily made 

 manifest by the ordinary tests: in the latter no traces of copper could be 

 discovered. The back of the paper presented a green tint, having been 

 torn from a wall which has probably been painted with Scheele's green; 

 and matter scraped away from any part of the back was found to contain 

 copper. Since, however, the stains in front were manifestly superficial, 

 the discolouration being entirely removed by scraping, and since there was 

 no appearance whatever of staining at the back of the paper, nor of any 

 effect of the electrical discharge, it was impossible to attribute the stains 

 to copper produced from the Scheele's green on the wall below the paper. 

 Dr. Thomson, therefore, considered the most probable explanation to be, 

 that the stains of oxide of copper must have come from the bell-wire. To 

 ascertain bow far this explanation could be supported by the circumstances 

 of the case, I wrote to Mr. Leitch asking him for further particulars, espe- 

 cially with reference to this point, and I received the following answer : — 



" MONIEMAIL, CuPAR-FrFE, 



30th Nov., 1849. 



" * * I received your letter to-day, and immediately called at 

 Ilall-hill, in the parish of Colessie, the farm-house which had been struck 

 by the lightning. * * 



" I find that Dr. Thomson's suggestion is fully borne out by the facts. 

 I at first thought that the bell-wire did not run along the line of dis- 

 colouration, but I now find that such was the case. * * 



[From a drawing and explanation which Mr. Leitch gives, it appears 

 that the wire nuis vertically along a corner of the room, from the floor, to 

 alwut a yard from the ceiling, where it branches into two, connected with 

 two cranks near one another, and close to the ceiling.] 



