167 

 ON LUMINOUS WOOD* 



(To the Editor of the West of England Journal.) 



In an Essay read at the Bath Literary Institution in the year 1830, I 

 endeavoured to shew that the appearances of fire, or light moving flames, 

 (said to be occasionally seen in marshes, and sometimes also on dry downs j) 

 the objects of superstition, and subjects of poetry, cannot with any proba- 

 bility be referred to any one physical object or class of objects, or cause of 

 luminous appearance. That the names, " Will-o'the-Wisp," " Jack-o'- 

 Lanthorn," " Ignis fatuus," &c. have been given to fire seen at an unknown 

 distance, proceeding from many different causes, from lanthorns of night 

 fishermen or bird catchers, from gypsey fires, from burning weeds, and 

 from peat or lime-kilns. 



In Kirby and Spence's Entomology, vol. ii, p. 422, is a clear discrimi- 

 nation between meteoric and electric fires, and another class of luminous 

 appearances, namely, those known to proceed from insects. To the latter, 

 the Ignis fatuus described by Derham, (Philosophical Transactions, 1729,) 

 is correctly attributed ; and it is clearly shewn that many similar delusions 

 admit of similar explanation. 



There is, yet, one kind of terrestrial phosphorescence, perhaps less com- 

 monly seen than the light of the glow-worm, (lanipyris nocturnal) yet not 

 uncommon, namely, the luminous appearance of decayed timber, called 

 touch-wood. 



Pieces of dry wood, so soft as to crumble when pressed between the 

 finger and thumb, were brought to me from a coppice. They were not 

 uniformly luminous, but each piece, about the size of my hand, exhibited, 

 as nearly as I can remember, at least half a dozen luminous spots, less 

 brilliant than the light of the glow-worm, but rather like the bluish sparks, 

 perhaps of minute Medusa3, not unfrequently visible on oyster shells. 

 From what cause does this phosphorescence proceed r If every rotten 

 stake were phosphorescent ; every heap of rotten vegetables, every hop- 

 bed, were luminous ; the reply would be, " Putrescent plants always pro- 

 duce phosphorous ;" and so inquiry might end. But it is not so. Rotten 

 wood and leaves are not always, but are rarely luminous ; and it is this 

 rarity which gives occasion to the following questions. 



1. Has the timber of various trees, in a decayed state, been found to 

 exhibit phosphorescence ?t 



2. Does the phosphorescence proceed from any stage of fermentation ? 



• This and the preceding paper have come to us anonymously ; we shall be obliged 

 to any of our readers who will further elucidate the subjects to which they relate. — Ed. 



t A very general belief amongst woodmen and gardeners is, that phosphorescence 

 is peculiar to the decayed ash ; a friend assures me that he has seen it in willow 

 wood. My first-mentioned specimens were from an ash tree; I kept them during 

 the day in a dry place ; on the following night they had ceased to be pho.sphorcscent. 



