264 Messrs. Langley and Very on the 



Its light was instantly extinguished thereby, and did not 

 revive. The experiment was repeated, and with the same 

 result. 



Macaire * (quoted by Becquerel) found that the luminous 

 matter taken from the body of a glow-worm and heated, in- 

 creased in brilliancy up to a temperature of about 41 D C, after 

 which the light diminished, became reddish, and ceased at 

 52° C. An electric current increased the luminosity in both 

 the living insect and in the luminous part separated from the 

 remainder of the body, but ceased to have any effect in a 

 vacuum. Oxygen and carbon monoxide increased the light 

 of the living insect and of the luminous matter taken from its 

 body ; but the light ceased in a vacuum, in hydrogen, in 

 carbon dioxide, in sulphurous anhydride, and in sulphuretted 

 hydrogen. 



Cams t observed that the luminous matter taken from the 

 body of the glow-worm ceases to shine when dried, but glows 

 again when moistened. 



Matttucci \ found that the phosphorescent substance of the 

 Italian glow-worm (Lampyris italica) soon ceased to glow in 

 hydrogen or in carbon dioxide, but shone decidedly brighter 

 in oxygen than in air, the oxygen being consumed and carbon 

 dioxide appearing. He drew the conclusion that the produc- 

 tion of light in this insect is entirely due to the combination 

 of oxygen with carbon, which is one of the elements of the 

 phosphorescent matter. The greatest brilliancy occurred at a 

 temperature of 37° or 38° Cent., but all phosphorescence 

 ceased above 50° or below — 6° Cent. 



Robert § found that a glow-worm cut in halves continued 

 to glow for half an hour, when the light ceased, but com- 

 menced again on the near approach of a candle, and continued 

 as bright as ever for thirty-six hours, after which it was 

 impossible to renew it. 



Pasteur || has examined the spectra of our Pyrophorus 

 without finding any appearance of bright or dark lines. He 

 states that M. Gernez has made a similar observation on the 

 spectrum of the glow-worm. 



Becquerel^ gives a good summary of the results of previous 

 observers. Since phosphorescent solids give banded spectra, 



* Bibliotheque Universelle de Geneve, 1821. 



f Analecten zur Natur- mid Heilkunde, Leipzig, 1829 ; see also Co?nptes 

 Rendus, lix. p. 607 (1864). 



\ Ann. de Chim. et de Phys. [3] ix. p. 71 (1843) ; also in Comptes 

 Rendus, xvii. p. 309. 



§ Comptes Rendus, xvii. p. 627 (1843). || Ibid, lix. p. 509 (1843). 



% La Lumiere, 1867. 



