in drffcrent Kitids of Gas. I77 



with the nature of atmofpheric air and the different kinds of 

 gafcs, as afcertained by chemical experiments, can hardly be 

 admitted, and is contradiiied by lliis circumftancc : thatj 

 according to every obfervation^ the ftate of the air, whether 

 moift or dry, cloudy or rainy, does not aher, or at leaft in a 

 fenfible manner, tlie velocity with which found is coiidu6tcd. 

 Various other conjectures feem to be equally inconfiftent with 

 nature. From the prefent experiments it follows, in my opi- 

 nion, that the velocity of the vibrations of an expanfiblc fluid 

 fubftance cannot be determined by the mechanical princi- 

 ples hitherto admitted alone; but that it depends, befides 

 thefe, upon other properties. 



Were the before-mentioned datafufficient to determine the 

 vibrations of an expanfible fluid, the tone which a pipe can 

 emit, both in the air and in different kinds of gafcs, under 

 like circumftances, would be inverfelv as the fquarc root of 

 the fpecific gravity of the expanfible fluids. The refult given 

 by the prefent experiments is, however, different. As I v>'as 

 not furnifhed with the apparatus proper for the purpofe, I 

 requefted, during my rcfidence at Vienna, profcffbr Jacquin 

 junior, who has a great zeal for the progrefs of fcience, to 

 undertake the experiments; and he w-as fo good as to comply 

 with my wifhes. 



The apparatus confiffcd of an open tin organ-pipe, in 

 which the length of the vibrating column of air from the 

 aperture where the inflated air ifliies to the end was about 

 fix inches, having its upper end inferted in the neck of a 

 bell-glafs, that could be clofely fhut by means of a cock. 

 On immerfing the bell in water, the pipe was at the fame 

 time filled with it, to guard againfl all mixture of atmo- 

 fpheric air. A bladder, furnifficd alio w'^\ a cock, was 

 fcrewcd upon the neck of the bell, after having been com- 

 prefl'ed. as much as pofTiblc, and emptied of air by applying 

 the movKh to it. The bell and the bladder were then fiiicJ 

 with fuch a ([uantity of the air to be examined, that the 

 water, in which the bell was immcrfcd, ftood at an equal ^ 

 T 3 height 



