1 8 On the Light emitted hj rotten IVood 



other mines amounts to about 20,000,000 of myriagrammes 

 per annum. The mean price of these coals at the mine is 

 1 1 cents per myriagranimc. 



[To be coQtiniied.] 



III. Ol'servafions and Experiments on the Light emitted by 

 rotten IVood in the different Kinds of Gas, and in Fluids. 

 By C. W. BocKMAN, of Carlsriihe*. 



JNoTWiTHSTANDiNG the o-reat number of accurate expe- 

 riments and of ingenious observations which have been al- 

 ready made known by several eminent philosophers in re- 

 gard to the light emitted by rotten wood in the different 

 kinds of gas and other mediums, it is still difficult to ex- 

 plain this phaenomenon in a satisfactory manner ; and this 

 difficulty is increased, because great variations occur both in 

 the observations, and in the consequences deduced from 

 them. 



Thus Spallanzani found a perfect analogy between the 

 luminous appearance of rotten wood and that of phospho- 

 rus f ; and conjectures, that by the putrid fermentation of the 

 wood its hydrogen and carbon come more readily into con- 

 tact with the oxygen of the atmosphere ; and that this com- 

 bination is a slow combustion, which occasions the luminous 

 appearance of the wood. In the non-respirablc gases this, 

 according to Spallanzani's opinion, cannot take place for 

 want of oxvgen ; and he infers that every kind of rotten 

 wood is not luminous, because the necessary quantity of 

 hydrogen and carbon docs not always happen to be extri- 

 cated at the same time. 



On the other hand, Mr. Carradori % is of opinion, from 

 other experiments, that rotten wood emits light without this 

 slow combustion taking place, and that the non-respirable 

 gases make on the wood onlv a transient impression capa- 

 ble of preventing the etHux of light, which, on the con- 

 trary, is promoted and increased by the peculiar action ot 

 oxygen gas. The observed decrease in the volume of the 

 oxygen gas he considers as not decisive, because this de- 



■' Schercr's Ai'gtmeinci Journal dcr Chrrilr, vol. v. no. i. 



f Sec an Essay on the Phsn-mena of natural Phosphorus in Atmo- 

 spheric Air, Oxygen Gas, and other Kinds otG.s, by L. Spallaniani. 

 Grtn's Annaltn dtr Physik, vol. i. p. i. 



X See Annalen der Phjsik, vol. i. p. i. 



- crease 



