100 Lanyley and Very — Cheapest Form of Light. 



Nathaniel Hulme. 1 — Exper. 6. A dead shining glow-worm 

 was put upon water, contained in a wide-mounted phial, at the 

 temperature of 58. The phial was then sunk in boiling hot 

 water, and as the heat communicated itself to the contents of 

 the phial, the light of the glow-worm became much more vivid. 



Exper. 7. Another lucid dead glow-worm was put into warm 

 water, at 114, to see if that degree of heat would extinguish 

 the light ; but on the contrary its glowing property was aug- 

 mented. All the water was then poured off, yet the insect 

 continued to shine for some length of time. 



Exper. 8. Two living glow-worms were put into a one ounce 

 phial, with a glass stopple ; and though they were perfectly 

 dark at the time, yet if the phial was briskly rubbed with a 

 silken or linen handkerchief, till it became pretty warm, it 

 seldom failed to make them display their light very finely. 

 This experiment was very frequently repeated. It had the 

 same illuminating effect upon the light of a dead glow-worm. 



Exper. 9. The complete influence of 212 degrees of heat 

 was now applied to the light of a glow worm, by pouring upon 

 one when dead, but in a luminous state, some boiling water. 

 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° C, after 

 w T hich 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 car- 

 bon dioxide, in sulphurous anhydride, and in sulphureted 

 hydrogen. 



Cams* observed that the luminous matter taken from the 

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

 again when moistened. 



Matteucci i found that the phosphorescent substance of the 

 Italian glow-worm {Lam/pyris Italicd) 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 



1 Philos. Trans., Roy. Soc. London, vol. xc, p. 180-181, 1800. 



2 " Bibliotheque Univ. de Geneve." 1821. 



3 "Analecten zur JSTatur- und Heilkunde, - ' Leipzig, 1829; see also Comptes 

 Rendus, lix. p. 607, 1864. 



4 "Ann. de chim. et de phys.," Ill, ix, p. 71, 1843, also in C. R., xvii, p. 309. 



