Chemistry and sce dae 141 
f=, (1+at)" while a is the coefficient of expansion of the gas 
taken as a basis of the calculation, then the e pe ices of Ober- 
mayer give the croomeias. values of 2 :—Air, 0°76; hydrogen, °70; 
14 
oxygen, 80; ¢ ; ethylene, 96 ; ; nitroge en, ‘74; pro- 
toxide of nitro ; 93; ¢a arbonic acid, 94; ethyl chloride, "98. 
The coefficient of ‘ietion of the permanent gases is, according 0 
these experiments, approximately proportional to "the 2 pow 
and that of the -soersible gases to the I-power of the absoluee 
temperature 
For temperatures: age 150° and 300° C. air gave the same 
values of n as between the lower temperatures —21°5 and 53°5. 
80. 
Pal ellascoes Sounding of two apa —Dr. R. Konre “ns 
i 4 the results of an elaborate series o be ese cie of the effect 
of two tuning forks sounded together as follow 
I, (1) The eerie of beats of two notes n, n’ is ears equal 
to the positive and negative remainder of the division — —; that is, 
equal to the numbers m, m’, which are produced ed ‘ttle n= 
“el aa +1)n —m’, while m, »' are the number of double 
n!' 
i, The cause of the beat-notes is simply the periodical coinci- 
ence of the co ommon maxima of the two sound-waves. 
(2) Th 
the relations 1: 8 and even 1:10, and may, as well as the beats of 
the unison, be regarded as penal directly from the composition 
of the vibrations of the primary notes, without the help of result- 
ant intermediate note es, whose existence cannot be proved. 
®) oth the beats m and the beats m’, not only of the interval 
nN; m, but also of the interval x» : hn--m (h=2, 3, 4), when 
the fi intensity of the shared notes and their number are ‘sufficient, 
a Ly into Shea no 
ry notes. 
fi en the be phan | of the beat-notes i whieh they are 
> ei and their numbers are sufficien t, these fe cute pace 
nge to a ssidean beat-note, as prim beats change to a 
Primary beat-note. > primary 
OL (6) The AUfedenecunttes and summation-notes, which 
