EtECTRIC XIGHT. ' 281 



IV. 



On the Absorpilon of Electric Light bi/ different Bodies. 

 In a Letter from Mr. Wm.^krimshirt., Juii. to Mr. 

 CuTiiijKRTsox, Pliilosophical Instrument Malcer^ Po" 

 land Street^ Soho. Communicated by Mr. Outhbertson, 



Dear Sir, 



I 



F you think any of the following fact.^ worthy of 

 publicity, you are at liberty to make what use you please 

 of them. 



You know that if a shock be passed through or over Electric light 

 the surface of a lump of sugar, the electric light is ab- renders sugar 

 sorbed, and the sugar becomes luminous. This circum- 

 stance induced me to try if other substances did not pos- 

 sess the same property, and with this view I have under- 

 taken a course of experiments, beginning with the calca- 

 reous substances, which genus I have already gone 

 through as far as circumstances would permit me. Whe« 

 ther or not the same thing has been undertaken by others 

 I do not know, but as far as my reading enables me to 

 decidtf, I think it has not; at least with the sole view to 

 the phosphorescence of these substances systematically 

 pursued, the path is clearly untrodden. 



My mode of making the experiments was as follows : 

 I placed the substance to be tried on a brass plate, New cxpecir 

 which, by means of a piece of thick wire, was fixed h'ori- ^lents. 

 zontally on the knob of the prime conductor, and endea- 

 vouring to take the spark from it by means of the ball 

 of the discharger. It was afterwards placed upon a 

 table, or wooden stand, and the shock from a Leydcn 

 phial, first passed over it about a quarter or half an inch 

 above its surface, by resting the ])oints of the discharging 

 rods at an inch or more distance from each other, uj)on 

 the stone to be tried. It need scarcely be observed that 

 ill Ihc iollovving experiments it is necessary to close the 

 eyes until the explosion be heard. Some of the results 

 were very beautiful and curious. 



All the calcareous species which I tried were more or 

 A'oL. XV.— Dec. 1806. Ql less 



