418 
POPULAR SCIENCE REVIEW. 
papers upon the question, and appears inclined to adopt the supposition 
that the spheroidal condition under ordinary circumstances is due to the 
existence of a layer of vapour which prevents contact between the globule 
and the surface beneath. This opinion is borne out by the fact that, in 
damp or wet weather, the duration of the globules is much diminished. 
There is certainly no contact between the globule and film. This may be 
proved in several ways : — (1) There is a slight depression in the film, just 
below the globule, and this depression accompanies the globule when it 
rolls about as it sometimes does. (2) The drop may fall with some force 
from the end of the glass rod, as from the height of an inch, and roll about 
without being absorbed. (3) The glass rod, with the drop hanging from 
it, may be lowered upon the film several times, so as to flatten the drop, 
without its being absorbed. In some cases, however, there is contact 
between the spheroid and the surface beneath at a single point ; for in 
rolling about the spheroid will sometimes leave a trail of liquid, and so 
diminish in size until it suddenly vanishes by being absorbed. Whether 
it be rolling about or stationary, the spheroid displays by the rapid motions 
of its particles the struggle that is going on between gravity and cohesion. 
If a minute portion of lycopodium powder be shaken over the globule, and 
this rude treatment does not cause it to break up, the powder will be seen 
streaming rapidly down the outer surface of the spheroid, and ascending 
by the central vertical axis to separate again at the top, and stream over 
the surface again to the bottom — presenting, in fact, a figure something like 
that given in books to illustrate the boiling of water. — Vide Philosophical 
Magazine , December. 
Characters of Drops of Liquid. — From Mr. Tate’s article in the Philo- 
sophical Magazine the following conclusions relative to the magnitude and 
other characters of drops of liquid may be drawn: — 1st, That other things 
being the same, the weight of a drop of liquid is proportional to the 
diameter of the tube in which it is formed. 2nd, The weight of a drop is 
in proportion to the weight of water which would be raised in that tube by 
capillary action. 3rd, When a drop is formed on a circular surface at a 
temperature of 50°, the augmentation of weight is in proportion to the 
diameter of the surface on which the drop is formed. 4th, The weight of a 
drop of liquid, other things being the same, is diminished by an augmenta- 
tion of temperature. 5th, Independently of density, the chemical com- 
position of a liquid affects the weight of its drop in a remarkable manner. 
6th, When the molecular force of cohesion is greatest, cceteris paribus , the 
weight of the drop is least, and conversely. 7th, In different solutions of 
chloride of sodium, the augmentation in the weight of the drop is in pro- 
portion to the weight of the dry salt in solution. — See Philosophical Maga- 
zine for March. 
Peculiar Properties of Ice. — Professor Tyndall publishes a letter received 
by him from Professor Reusch, of Tubingen, in which some of the characters 
of ice not hitherto observed are pointed out. In speaking of the division 
of particles of ice he writes : — “ In dividing these precious plates of ice, I 
soon found that it was necessary to handle them like glass. If the convex 
blade of a knife be passed over a piece of ice with a certain pressure, a 
sharp crack will result, and the plate may be broken in the direction of 
