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- appearances. For, it was sometimes globular, or else pointed like 

 the flame of a candle ; afterwards it would spread itself, and involve 

 our whole company in its pale and inoffensive light; then at once 

 contract, and suddenly disappear. But in less than a minute, it 

 would begin again to exert itself as at other times; running along 

 from one place to another, with great swiftness, like a train of gun- 

 powder, set on fire ; or else it would spread and expand itself over 

 more than two or three acres of the adjacent mountains; discover- 

 ing every shrub and tree that grew upon them. The atmosphere 

 from the beginning of the evening, had been remarkably thick and 

 hazy ; and the dew, as we felt it upon our bridles, was unusually 

 clammy and unctuous*. 



The late discoveries in chemistry, give us reason to hope, that 

 an explication of this extraordinary appearance may, before long. 

 be obtained. It is generally attributed to some inexplicable agency 

 of the electric fluid on the inflammable air of marshes ; but it seems 

 rather to depend on some hitherto unknown combination of phos- 

 phorus, with carbon or sulphur, in hydrogen gas, separated from 

 the wetted vegetable mould. 



It is true, that on phosphuretted hydrogen gas coming in contact 

 with the atmosphere, actual inflammation takes place ; whereas in 

 ignes fatui the illumination appears to be that of phosphorescent 

 light only ; but that the subsequent industry of chemists will 

 enable them to imitate this phenomenon still more closely, seems 

 very probable. Indeed, there seems to be reason for expectation, 

 that such a result may be the reward of a careful series of experi- 

 ments, in which the phosphorus is combined, in different doses, 

 with other gases, containing various proportions of the several sim- 

 ple combustible bodies perhaps the gaseous oxide of carbon might 

 be found well calculated to repress the combustion, whilst it per- 



* Travels, or Observations relating to several parts of Barbary, and the Levant, by 

 Thomas Shaw, D.D. F.R. S. 2d edition, 1756, p. 334, 



