0$ MUSICAL SOUNDS PRODUCED BY HI0ROGEN GAS. 



aclion of caloric on the vapour and its re-action on the atmo- 

 but to a tremu- fphcric air. I conceive that this phenomenon takes place in 

 andVonu-aAion *' ie f°M ovv i n g manner : The vapour contained in the bulb, by 

 of the vapour j means of an addition of caloric applied on all fides and in- great 

 ftrikes the*air quantity* acquires an augmentation of volume and elafticity ; 

 and produces it rapidly pa ties from the bulb into the tube, and drives out the 

 found. a j f con t a ined in it ; but this air and the fides of the tube caufe 



it again to lofe a portion of its caloric, and its volume imme- 

 diately diminifhes. A vacuum is thus made, and the air re- 

 fumes its primitive fituation. Another addition of caloric re- 

 frores its elafticity, which it fpeedily lofes in the fame manner. 

 A feries of ofcillations by this procefs give the air an undulat- 

 ing motion ; and the waves being reflected by the fides of the 

 tube, become fonorous and appreciable as foon as their pro- 

 grefs and recefs are ifochronous with the ofcillations produced 

 Itfeemsas iftheby the caufe here pointed out. There are fome tubes which 

 the P vapour ought never produce any found : In this cafe I prefume that the ad- 

 to be ifochronous vance and recefs of the waves cannot harmonize with the pri- 

 W!t a h clion of the mitive ofcillations, but that the one deftroys the other. After a 

 tube governed by certain time the found diminifhes and dies away: This is ex- 

 its length and pi ame d by t he propagation of the heat along the fides of the 

 Thefe founds tube when the bulb is very warm and the tube cold. The 

 ceafe as foon as vapour when firfr driven from the bulb, fuddenly lofes a part of 

 come too hot to» ts volume, and the ofcillations thus produced are flrong and 

 occafion the fud- frequent; but when the tube has acquired a certain degree of 

 o^the va'pour! 11 neat > * ne vapour then gradually diminilhes in volume as it pafTea 

 from a very high temperature to a fituation certainly lefs warm, 

 though of a fufficient degree of heat to caufe the ofcillations to 

 Experiments in become weaker, and at length entirely to ceafe. That this is 

 confirmation. {he caufe of the cen - at i on f tne found, may be fhewn by apply- 

 ing a flrong heat to the part of the tube already warmed, and 

 at the fame time keeping up the firft degree of heat at the bulb. 

 By this means the limit of temperature is again precifely deter- 

 mined, and the found reproduced in all its force. It may ealily 

 be conceived that the fubitance of the tube ought to-be a non- 

 conductor of heat, and on this account glafs is preferable to any 

 other fubitance. 

 Concerning the Let us now compare the tubes which found by means of hi- 

 founds producedj r0 g en w j tn tno f e w j tn bulbs. In the former we have every 

 Repetition of condition necefTary to the production of found ; a very hot 

 the theory ai- va p ur, and confequently very elaftic : for as we obferved, 



ready dated. J ** J J ^ 



