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for 30 seconds, and finally became black. In muri- 

 atic acid, specific gravity 1.12, the light remained for 

 24 seconds ; but in nitric acid, specific gravity 1.4-5, 

 it was only luminous 10 seconds. In a subsequent 

 experiment with sulphuric acid, specific gravity 1.85, 

 it remained luminous only 20 seconds. In alcohol, 

 specific gravity .812, the luminous appearance lasted 

 nearly two minutes; and in camphorated spirit of 

 wine, the same period ; in caustic ammonia it was lumi- 

 nous for 60 seconds ; in almond oil, and in water at 

 68 Fahrenheit, it continued luminous for some hours, 

 but was much less brilliant and beautiful than when 

 immersed in oil of olives. When put into olive oil, 

 at 11 o'clock, P.M., it continued to yield light through 

 the entire night, and several successive ones : when 

 reposing in this tranquil medium, and viewed at a 

 distance of about 10 feet, it twinkled like a fixed star ; 

 and although the eye steadily and tranquilly observed 

 the beautiful phenomenon, the light seemed subject 

 to occasional occultation, as if some axal revolution 

 had been super-induced ; and this curious eclipse 

 took place in periodic times but we could not de- 

 termine whether this phenomenon was dependent 

 on some property inherent in the light, or the result 

 of circumstances connected with the organ of vision, 

 or the air. Two glow-worms were shut up in a 

 dark box from Tuesday morning to Saturday night ; 

 yet, when then examined, were shining with great 

 brilliancy a fact which tends to prove that previous 

 exposure to light is not necessary to their luminosity, 

 and conjoined with the circumstance that during day 

 they penetrate to the roots of the grass, or moss, 

 would lead us to conclude, that solar light, on the 

 contrary, is injurious. When we breathed on a glow- 

 worm not previously shining, it became luminous 



