EULOGY ON GAY-LU$SAC. 161 



instantaneously, as if struck by a thunderbolt. The odor of bitter 

 almonds which is exhaled, it is said, by the dead bodies of animals that 

 have perished from the effects of hydrocyanic acid, would then have 

 given no clue to the cause of this national catastrophe. 



SIPHON BAROMETER — MANNER IN WHICH CLOUDS ARE SUSPENDED — 

 STORM-CLOUDS — DIFFUSION OF GASES AND VAPORS— CENTRAL HEAT 

 OF THE GLOBE. 



Gay-Lussac published, in 1816, the description of a portable siphon 

 barometer, now so widely spread, especially since the improvements 

 made in it by the artist Bunteu. 



This is not the only service rendered to meteorology by our friend. In 

 a note inserted, in 1823, in the twenty-first volume of the Annates de 

 Chimie et de Physique, (Annals of Chemistry and Physics,) he has ex- 

 plained his views on the manner in which clouds are suspended. On 

 looking at the ascensional motion that the ascending atmospheric cur- 

 rent gives to soap-bubbles, evidently heavier than the air, he thought 

 he might attribute the suspension of vesicular molecules to this same 

 current, at much more considerable elevations. 



Before this epoch, in 1818, in a letter addressed to M. de Humboldt, 

 Gay-Lussac had investigated the causes of the formation of storm-clouds. 

 According to him, the electricity constantly diffused in the air suffices 

 to explain the phenomena presented by this kind of cloud. When the 

 storm-clouds are of great density, they possess the properties of solid 

 bodies; the electricity originally disseminated in their masses rises 

 to the surface where it has considerable tension, by virtue of which it 

 can overcome, at times, the pressure of the air and dart forth in long 

 flashes, either from one cloud to another, or over the surface of the 

 earth. It will be seen how greatly these views differ from those of 

 Volta, the master of everything connected with electricity. Whatever 

 be the opinion pronounced upon the rival theories, it must be acknowl- 

 edged that in the discussion of what Gay-Lussac calls his conjectures, 

 he has shown himself a very skillful logician and perfectly familiar with 

 the most subtile properties of the electric principle. 



Among the researches of our friend, designed to throw light upon the 

 nicest points of meteorology, we must also mention those which concern 

 vaporization and the dissemination of vapors, either on empty spaces 

 or in spaces containing aeriform fluids. 



I perceive that I shall scarcely be able to say even a few words about 

 Gay-Lussac's views with regard to volcanic ph enomena. These opin- 

 ions were published in 1823, under the title of Eejlexions, in a memoir in- 

 serted in the twenty-second volume of the Annates de Chimie et de Physique. 

 The author does not believe that the central heat of the earth, if that heat 

 exist, contributes at all to the production of volcanic phenomena. These 

 phenomena, according to him, are owing to the action of water, probably 

 s 11 



