— 17S — 
on leaving the solid being remarkably sudden. Curve B, Fig. 
II. , shows the relative quantity of liquid passed in a unit of 
time. The abscissae give the value of gt and the ordinates 
the value of column 3 Table V. 
In order to avoid the influence of variations in rate we shall 
for the future take the rate of dropping in all cases the same 
and unless the contrary is stated the rate adopted will be 
9t — 2”. 
The factor, the influence of whose variation on the size of 
the drop we have- next to consider, is tire constitution of the 
liquid of which the drops arc formed. For the above experi- 
ments concerning the influence of rate cocoanut oil was em- 
ployed on account of its non-volatility. On allowing a quan- 
tity of it having an exposed surface of about two square 
inches to stand for 70 hours it was found to have increased 
about two milligrammes in weight, probably in consequence 
of oxidation: Its fixedness therefore and its perfect liquid- 
ness at the temperature 28° — 30 w C. make it well adapted for 
this special purpose. Chemically and physically however it 
is of little interest from the present point of view, because it 
is a mixture of several substances the proportion between 
which is indefinite. 
It will be of great interest to examine the effect upon the 
size of drops of the chemical composition of liquids belonging 
to the same homologous series, such as the ethers, alcohols 
and corresponding acids. For this purpose and also for exa- 
mining the effect of solution of solid matter upon the drop- 
size we must determine the drop-size of water under fixed 
conditions. 
With mere mobile liquids, the Apparatus Fig. 1 fails to 
give a strictly uniform flow. As the liquid descci ds in B it 
adheres by capillary action to the lip of A for some time af- 
ter the level of B is below the lip. The air at last separates 
. the two, enters the flask A displaces the liquid there and res- 
tores the level to B. So that although tbc average height of 
13 is constant yet it undergoes a series of slight but ceaseless 
