Chemistry and Physvs. 589 
Compound Ethers. 
Propyl acetate, CH,.C-.-O---CH,.CH,.CH, 101-98° 
Ethyl propionate, CH, .CH, dr tial ee .CH, 98°8° 
If we compare together methyl butyrate 
CH,.CH,.CH, .C--.0-.-CH,, with rn propionate 
i 
CH,.CH,.C---O-.--CH,.CH,.CH,, the first of which boils at 102° 
\ 
u 
the last at 122°44°, it would at first seem as if this law was con- 
tradicted; since the linking oxygen atom in the latter is exactly 
in — middle of the chain. But the explanation of this apparent 
maly is found in the fact, readily observed on comparing 
newbie butyl propionate CH, .CH aU -O-.-CH,.CH,.CH,CH,, 
é 
and propyl butyrate, OBE CR la a boil- 
ing, the one at 145°99°, the other at 143°42°, that for an analo- 
gous position of the linking oxygen atom, the influen ce of the 
1874 4, 
On the Vibration of Liquid Surfaces. Bune oat a 
mijn to investigation the undulations which are poet 
upon liquid surfaces when these are thrown into vibratio n- 
stead of producing the motion of the liquid by, a sudden sete or 
an upward movement, as in the case of Faye’s experiment, the 
author made use of a heavy tuning fork for this purpose, the 
vessel containing the liquid being in contact with it, either 
directly or through the intervention of the table on which both 
rested. The best results were obtained, however, when the vessel 
r 
board of a piano. In this way the surface of the liquid assum 
a fixed condition of elevation and depression, the result of uni- 
form vibration over its entire area. The phenomenon may 
observed either obese 2 by a small telescope, or better at pmnjen- 
tion upon a screen. For this purpose, a beam of sunlight 
