Chemistry and Physics. 217 
minutes at Geneva, and this is explained by the narrowness of the 
neck of the lake at the latter place. This period he proved to be 
For shallow lakes the period is lengthened, and his observations 
show that the period is a function of the length and depth and that 
longitudinal and transverse waves may coexist, just as Prof. Guthrie 
has shown to be the case in troughs.— ature, xiv, 164. ©. ©. P. 
9. Lriction of the Ether.—Mr. W. M. Hicks drew the atten- 
oO 
~ 
18 supposed that the disc, through the rapid rotation, has ex- 
panded and consequently been lowered in temperature, that whilst 
rotating it is raised to the temperature of the surrounding region, 
and, therefore, when the rotation is stopped, and the disc has 
shrunk to its former size, it will give out the heat it had taken in 
whilst rotating. In the case of silver it was shown that the dise 
ougat to show a rise of -4°C., if the rotation had been continued 
for some time, and this was compared with the rise of ‘47°C. which 
century by something like -006’.— Nature, xiv, 144. Be. P, 
10. Specific heat of Gases.—M. M. Kunpr and Warsure have 
mercury vapor which has been supposed by chemists to consist of 
monatomic molecules, According to the Kinetic theory of gases, 
gases may pro 
their molecules, e method here employed was to produce a 
b 
Applying the formula for the velocity of sound which includes 
the densities, temperatures, and the ratio of the specific heats, and 
taking as the value of this ratio in the case of air, the number 
1405, they obtain, for mercury vapor the number 1°67, which may 
be considered as fully in accord with the number 1°666 furnished 
by theory.— Pogg, Ann., iii, 1876. Nature, xiv, 182. £. C. P. 
