544 Intelligence and Miscellaneous Articles. 



some of which, he observes, are new in part, and others more accu- 

 rately determined than heretofore : — 



1. The phosphorescence of a glow-worm may cease hefore its 

 death. 



2. There exists in the glow-worm a substance which emits light, 

 unaccompanied by sensible heat, and this does not require for its ex- 

 hibition either the integrity or the life of the animal. 



3. The phosphorescence of the insect ceases in carbonic acid and 

 hydrogen gases in thirty or forty minutes, provided the gases are 

 pure. 



4. The light of the phosphorescent matter is decidedly brighter 

 in oxygen gas than in atmospheric air, and it preserves its brilliancy 

 for nearly three times as long. This occurs not only with the entire 

 insect, but with the luminous segments separated from it. 



5. The phosphorescent matter, when made to shine either in oxy- 

 gen or in the air, consumes a portion of oxygen, which is replaced 

 by an equal volume of carbonic acid gas. 



6. The phosphorescent matter, when in contact with oxygen, but 

 reduced to a state in which it cannot emit light, does not sensibly 

 absorb oxygen, nor does it develope carbonic acid. 



7. One proportion of oxygen and nine proportions of hydrogen or 

 carbonic acid gas, form a mixture in which the phosphorescence 

 continues for some hours ; it may therefore be concluded that it is on 

 account of the alteration which happens to the phosphorescent sub- 

 stance, that at the expiration of some days it ceases to shine, after ha- 

 ving been put into pure oxygen, a portion of which is eventually re- 

 placed by carbonic acid gas. The hydrogen in which several glow- 

 worms were placed for twenty-four hours was analysed, the insects 

 having shone for a few minutes only. The same happened if the gas 

 was pure, in operating over mercury, carefully filling the receiver and 

 reversing it two or three times to remove the air which adheres to the 

 glow-worms. In this hydrogen it was found that its volume was 

 slightly augmented ; with 8 cubic centimetres of hydrogen there was 

 an increase of c,c- 2 of volume which was absorbed by potash ; it was 

 therefore carbonic acid which the insects had produced, and this oc- 

 curred either because some oxygen remained in their tracheae, which 

 combined with carbon and converted it into carbonic acid, or because 

 the insects contained this acid ready formed. When the luminous 

 segments were alone carefully put into hydrogen, they continued to 

 shine for a few seconds only, and the gas suffered no change. 



8. Heat, to a certain degree, increased the light of the phospho- 

 rescent matter ; cooling produced the contrary effect. 



9. When the heat is too strong the phosphorescent substance is 

 altered, and the same occurs whether it be left in the air or in some 

 gas for a certain time, provided it be separated from the animal. 



10. This phosphorescent matter thus altered is not capable of 

 emitting light or of becoming luminous ; these facts evidently deter- 

 mine the nature of the phaenomenon ; the production of light in this 

 insect is entirely dependent upon the combination of oxygen with 

 the carbon, which is one of the elements of the phosphorescent 

 matter. — Ann. de Ch. et de Phys. S 3. ix. 71. 



