OBSERVATIONS ON SPONTANEOUS LIGHT. 103 



§ 7- 

 The Etftfts of nitrous Gas * on fpontaneous Light. 



EXPERIMENTS. 



Exp. I. A piece of frefli herring was introduced above Nitrous gas 

 water, into this gas, at 3 P. M. and remained there four nights, J^^L 3 "^^ 

 without emitting any light : it was then withdrawn, and ex- guifhes iponu- 

 pofed to common air, for the fpace of three nights ; but did neous h & ht * 

 not become lucid. 



Exp. 2. The fame experiment was made with a piece of 

 herring beginning to be luminous ; but its light was gradually 

 extinguished : it was detained in the gas for three nights, and 

 taken out dark. It was then expofed to the open air, for the 

 three fubfequent nights ; but its fhining appearance did not 

 return. 



Exp. 3. A cork with luminous matter, introduced above 

 water, into this fpecies of gas, had its light, in general, ex- 

 tinguifhed in from 10 to 30 minutes; and, when taken into 

 common air, its light very feldom re-appeared. 



Exp. 4. Fragments of fliining wood, above water, in nitrous 

 gas, were likewife commonly rendered dark in a very fliort 

 ipace of time, as in three or four minutes ; fometimes a frag- 

 ment, if uncommonly luminous, would no! be extinguished in 

 lefs than fix or eight minutes ; and very feldom would the light 

 revive, on expofing the wood to atmofpherical air. 



Exp. 5. A dead mining glow-worm being put above water, 

 into this gas, its light was quickly extinquifhed ; but, after 

 the infect was taken into the common atmofphere, the light 

 gradually returned. The experiment was thrice repeated, 

 and with the fame refult. 



OBSERVATION. 



This fpecies of gas, we obferve to have totally prevented 

 the emiffion of light, and to have quickly extinguifhed that 

 which had been emitted : likewife that the luminous objects 

 which had been under its influence, (except the glow-worm) 

 did not experience a revival of their light, when taken out, 

 and kept for fome time in common air. 



* This gas was obtained from copper and diluted nitrous acid. 



§ 8. 



