

MUSICAL SOUNDS PRODT7CED BY HIDROGEN GAS. 25 



being very elevated, thefe vapours muft occupy an extenfive 

 fpace ; but by immediately coming into contact with a cold 

 air, their volume muft rapidly diminim. A vacuum muft thus 

 be formed into which the air muft collapfe, and be again driven 

 by other vapours, which again contract in their turn. Do not 

 the vibrations refult from thefe alternate motions, produced by 

 the great expanfion and fubfequent contraction of the va- 

 pours * ? Such were the conjectures that might be formed as 

 to the probable caufe of the phenomenon ; but accident has 

 prefented me a fact which appears to give them fome weight. 



I had a thermometer tube of about one line in diameter, at Sound produced 

 the extremity of which was a fmall bulb : there was a drop of . by h « tin g w«« 

 water which I wifhed to expel from it ; for this purpole I re- ter bulb and 

 peatedly expofed the bulb to the flame of a lamp with alcohol, tubtr# 

 and was agreeably furprifed to hear a mufical found proceed 

 from the tube. 



In order that this experiment may fucceed, a tube of one, Inductions for 

 two, or three lines in diameter, fhouki be taken, of three, four, ma ! c5n g the ex- 

 or five inches in length, with a bulb at one of the extremities, 

 in diameter about three times that of the tube ; it need not be 

 very regular. If it were even a little flattened, I think the 

 fouud would be louder. A very fmall quantity of water or 

 mercury muft then be introduced, and expofe it to a ftrong 



* It appears probable to me, that the found produced by air pre- The found of air 



cipitating itfelf into a vacuum, is more intenfe than that refulting filing into a va- 



from an expanfive force. The horrible noife occafioned by the de- cuum . much 

 c r /• i • i • more intenJ k 



tonation or loap bubbles of hidrogen and oxigen is well known, than that from 



though the lighted objects furrounding the bafon are not even explofion. 

 fhaken. Whence it may be concluded, that the phenomenon is pro- 

 duced by the fudden vacuum proceeding from the deftruction of the 

 gafes. The detonation of a piltol with inflammable gas is much 

 greater than that of an air-gun, though the effect: is lefs conilder- 

 ablej probably becaufe a vacuum in the piftol fucceeds the firft ex- 

 panfive force. The child's toy, called the bumming top, is well The humming 

 known. It is a hollow fphere, with an opening at its circumference: top. 

 it produces a very ftrong humming noife when fpinned rapidly on its 

 axis. What may be the caufe of this humming ? I think it is the 

 fame as that which I have jure mentioned j the centrifugal force 

 drives the air from the fphere through the opening j a kind of va- 

 cuum is made, into which the external air continually prefTes, and 

 is conftantly driven backj whence proceed a feries of fonorous of- 

 cillations,'— D. 



heat 



