152 Miscellaneous Intelligence. 
action. He suggests that all gases may be considered as consist- 
ing of solid atoms of various sizes, enveloped by atmospheres of 
heat also very different, and that hydrogen though it has the largest 
atmosphere of heat, has the smallest atom, and is thus permitted 
to escape by fissures, which retain the other gases. “ Probably,” he 
says, ‘‘ fissures may be formed which will permit azote to pass, but 
not oxygen, and others again which will let the oxygen out, but 
not carbonic acid gas.” 
Another experiment which seems related to this subject is as fol- 
lows :—A thermometer-tube had been drawn out very fine in the 
lamp, and it being desired to have it filled with alcohol, the 
point was immersed in that fluid, and the bulb heated until no more 
bubbles of air escaped; the tube was then cooled, but no alcohol 
entered. When again heated abundance of bubbles of air passed 
out through the alcohol, though when recooled no alcohol would 
enter. Upon examining the tube with a lens, nothing was seen which 
could prevent the entrance of the alcohol ; on withdrawing the tube 
from the alcohol, the external air entered with a hissing noise. 
M. Dobereiner conceives that the diameter of the tube was so 
small that the alcohol could not enter, but only the air which it 
contained.—Ann. de Chim. xxiv. 332. 
5. Sound produced by opening a Subterraneous Gallery.—In the 
road made by Napoleon communicating between Savoy and 
France, and which passes by Chamberry and les Echelles, there 
is, as is well known, about two miles from the latter place, a gal- 
lery cut in the solid rock, twenty-seven feet high and broad, and 
nine hundred and sixty feet in length. Mr. Bakewell states in his 
travels, that this gallery having been commenced at both ends, 
when the excavations from each end nearly met, and the thin par- 
tition of rock between them was first broken through by the stroke of 
the pick,a deep and loud explosion followed resembling thunder. 
The cause of this explosion Mr. Bakewell thinks is easily explained. 
The air on the eastern side of the mountain being sheltered both 
on the south and west from the sun’s rays, must be frequently 
many degrees colder than that on the western side. The moun- 
tain rises full one thousand feet above the passage, and at least 
fifteen hundred feet above the bottom of the valley, forming a 
partition between the hot air of the valley, and the cool air of the 
ravines on the eastern side, and a sudden opening being made for 
the dense air to rush into a rarer medium, must necessarily pro- 
duce a loud report, just as a bladder does upon bursting in the 
rare air of a receiver. ‘The sound of the explosion being greatly 
increased by reverberation through the long archway on each 
side.—Bakewell’s Travels. 
This explanation of the origin of the sound seems insufficient to 
us, inasmuch as it would require a much greater difference of ba- 
