ox THE ADIABATIC RELATIONS OF ETHYL OXIDE. 
175 
all possibility of any marked friction effects occurring. The final result of such 
experiments is that the velocity of sound in hydrogen is to the velocity in air at 
the same temperature as the square roots of the specific volumes. Now the mean of 
nine readings with hydrogen, at ]7’5° C., gave 7’3r) centime, as the wave-length for 
the note of the vibrator. Taking the density of air as compared with liydrogen 
to be 14'47, this gives n — 17,526 per second as the frequency of the vibrator. 
(2.) Coiifirmatorij Experiments ii'ith Argon. 
Experiments were made lay one of the authors on the velocity of sound in argon ; 
these experiments were originally undertaken to determine the value of the ratio of 
the specific heats for argon, but as some observations were carried out with the 
actual tube described above, they can be used for our present purpose. The following 
are the measurements observed .— 
Mean of 40 readings in original tube with argon at 17'5° C. 
0 ° 
M 
Mean of C readings in wider tube with argon at 6 o° C. 
0 ° 
?5 >) >) 
Mean of 5 I’eadings in wider tube with argon at 8'64° C. 
Me.an of 11 readings in wider tube with argon at 1I'49° C 
Mean of 5 readings in wider tube wdth air at 0‘7° C. 
0 ° 
Mean of 5 readings in wider tube with air at 7'22° C. 
0 ° 
15 
iMean of 11 readings in wider tube with air at 11'2° C. 
I'SOS centims. 
1-753 
3-1 centims. 
3-064 
3-131 centims. 
3-083 
3-168 centims. 
3-103 „ 
3 373 centims. 
3-332 „ 
. 3-41 centims. 
3-366 
3-423 centims. 
3-355 „ 
From these numbers we easily find that the mean wave-length at 0° in the wider 
tube is for argon 3‘083 centims., and for air 3-351 ; this gives us n — 17,452 in the 
original tube. 
(3.) Confirmatory Experiments with the Phonograph. 
An attempt was made to discover the number of vibrations emitted per second by 
the rod with the aid of a phonograph. Such an experiment, if it could have been 
carried out, would have been extremely valuable as affording a direct determination 
of the frequency required. Unfortunately, the sound produced by the vibrator was 
too feeble to make a distinct impression upon the wax cylindei’. A long tube of the 
same kind of glass was, therefore, taken, and this produced a much graver and 
