54 
POPULAR SCIENCE NEWS. 
[April, 1891. 
[Original in Popular Science News.] 
WATER GLOBULES. 
BY L. S. FRIERSON. 
By striking the surface of a pond obliquely with 
aa oar, a shower of drops will be thrown up. Most 
of them will, when they fall, reunite at once with 
the sheet of water below. But some of them will 
not do so, but will float and roll rapidly about, 
looking like little spheres of quicksilver. These 
globules will, after floating a longer or shorter 
time, suddenly disappear, and leave no sign save a 
tiny ripple. Although these water balls are such 
common objects, yet they are well worth the stu- 
dent's attention. He can mauufacture them at 
will, and in a manner convenient for observation, 
by taking, instead of a pond of water, a china 
saucer filled with kerosene oil. The tension of 
the skin which all fluids seem to exhibit, and 
which accounts for the floating globules, seems to 
be greater in the case of the oil than in water. 
With the aid of a rod of wood the size of a pencil 
the apparatus is complete. By dipping the rod in 
and out we may obtain an abundance of the glob- 
ules whose antics we are to study. The first 
thing which attracts attention is, that often when 
only one drop of oil has fallen from the end of the 
rod we see two globules floating, and also, we ob- 
serve, that one of them is much smaller than the 
other. 
This is accounted for in this manner : As the 
forming drop receives accretions from above, it 
elongates until the accumulating weight becomes 
too much for the cohesion of the particles of oil, 
and it breaks away. But it does not break oft 
smoothly, but draws after it a tail like the stem of 
a pear. This stem then separates from the larger 
mass below, and lioth form themselves into 
spheres. The first and larger drop falls upon the 
fluid beneath, and swims thereon. The smaller 
drop falls upon the larger, and rolls rapidly down 
its side and away. Thus we account both for the 
two drops and for their disparity in size. We 
next observe that when two spheres approach 
sufficiently near they seem to be attracted by each 
other, and will coalesce into one larger globule. 
The question naturally arises. Why should the 
tension of the globules be suflicient to keep them 
from joining the fluid beneath, but not to pre- 
vent them from joining each other? The reason 
seems to be that each globule swims iu the bottom 
of a cavity, or depression, which is equal in bulk 
with the globule. Now when two globules ap- 
proach each other their depressions will begin to 
coalesce, and the globules will be driven toward 
each other, or, in other words, will roll flown hill 
to the center of their combined depression. The 
shock (combined with the fact that the opposing 
surfaces of the two spheres are very small) forces 
a rupture of their skins, and a juncture of the two 
results. 
We next observe that a ball will sometimes 
appear to suddenly shrink to a fraction of its 
former size. This is a rather uncommon behavior, 
bnt diligence will reward the student with this, at 
first sight, inexplicable phenomenon. If we watch 
attentively the behavior of a ball when It bursts, 
we will see that there is always an attempt to re- 
produce itself upon a smaller scale, after the fol- 
lowing fashion : If we throw a bullet into a pond 
of water it, in sinking, first sends out a wave, 
then, as it falls down, it leaves a cavity, and the 
water, rushing in to fill up the depression, meets 
at the center, and a column of water is projected 
•upward. The same process happens on a small 
scale when a water ball coalesces with the fluid 
below. First a wave is driven outward, then, as 
the globule sinks, it forms a depression. The 
fluid then rushes in ; a minute column is projected 
upward, and diWdes into one or more fragments, 
which, upon falling back, sometimes assume the 
spheroidal condition and float ; — all being done so 
quickly as to leave the impression that the first 
globule had shrunken to its latter condition. 
[Kate Field's Washington.] 
WHERE NATURE PLAYS SCULPl'OR. 
What looked like the fossil foot of a child, witli 
a little stocking on, was sent in to the National 
Museum the other Any. The most curious thing 
about it was that the stocking itself showed dis 
tinct signs of wear on the heel and ball of the 
foot. It was with regret, however, that the ob- 
ject was pronounced not a fossil nor a child's foot, 
nor }'et anything else save a concretion of silicious 
matter which had taken this strange form by pure 
accident. The imitation was so astonishingly 
exact that the mistake was not at all surprising. 
This is only one of many curiously imitative 
concretions which have been offered at various 
times to the Smithsonian Institution by persons 
who imagined them to be fossils. That it may be 
understood how they are formed, it should be ex- 
plained that matter in general has a tendency to 
segregate particles of the same kind gathering to- 
together. In the Connecticut River, for example, 
fine clayey particles are held in suspension by the 
water and swept along with the stream. Per 
chance some of them will collect about a pebble, a 
grain of sand, or any other hard object, subse 
quently gathering more about them until a lump 
of some size is formed, with the pebble or what 
not for a nucleus. Such lumps often take very 
queer shapes, and it is amazing how they some 
times imitate the familiar forms in nature. A 
favorite shape with them is one which so closely 
resembles that of a turtle that a specimen of the 
sort is, as a rule, mistaken for a fossil tortoise. 
Looking at it from beneath, the head, the four 
legs, and the tail are quite distinct, with the lines 
of the shell ; and yet it is only an accidental con 
cretion of clay. Spindles, rings, and Indian 
arrow-heads are other shapes which such con 
cretions take very jjerfectly. 
But clay is not the only form of matter which 
takes concretionary forms. There is a mixture of 
carbonate of iron and clay, which assumes very 
interesting shapes in the same way. One of these, 
very common indeed, is easily mistaken for a 
fossil peanut. Break one of these peanuts open, 
and you will invariably find a small spiral winkle- 
shell, which was the nucleus. Even more inter- 
esting are the bigger concretions of this "clay- 
ironstone," as it is called, which, having got into 
dry places, are dried by the sun. By this process 
such a lump is made to shrink, the water being 
withdrawn from it, and to crack toward the 
center. Afterwards, maybe, through the rising 
of a stream after a drought, the lump becomes 
submerged again, and its cracks and fissures are 
filled in with carbonate of lime, which all streams 
carry. Now, take such a lump, saw it in two, and 
you find that the sawed surfaces are like the most 
exquisite marble, the original material being inter- 
spersed with streaks of the carbonate of lime 
crystallized. In one locality in England these 
clay-ironstone concretions are found of very great 
size, and are used, when cut into slabs and polished, 
for the tops of tables and stands. 
There is a final ti-ansformation which the clay- 
ironstone concretion occasionally goes through, 
that produces the most extraordinary result of all. 
It may happen that the carbonate of lime which 
has entered into the mass is subsequently dis- 
solved out of it, leaving a chambered structure 
with walls and nothing else. People who find one 
such as this, very naturally imagine that it is the 
shell or skeleton of some remarkable dead animal, 
and take pains usually to send it to the nearest 
museum. 
Some time ago a physician sent to the National 
Museum a clay concretion, which he supposed was 
the fossil arm of a man. Another person contrib- 
uted an extraordinary stone of great hardness, 
which, when sawed through, was fountl to be of 
much beauty, though in the process it smelt very 
badly. When Curator Jlerrill saw the inside of it 
and observed its formation in concentric layers 
about a small, hard object as a nucleus, he knew 
that it was a calculus from the bladder of a hog 
or some such animal. 
By a curious inverse method of concretion all 
agates are formed. When certain rocks, ages ago, 
were in a molten state, great bul)l)les came in 
them and remained, in the shajie of cavities, when 
the period of cooling arrived. Into these cavities 
water, which percolates through all rocks, flowed, 
and deposited carbonate of lime [Qy. — Silicic acid'? 
— Ed.] upon the walls in layer after layer until 
the holes were filled up. Thus, when the rock is 
cut through, the lumps of agate are foimd. 
There is a queer sort of rock exhibited at the 
National Museum called "flexible sandstone." 
because it bends very easily. You take a long 
strip of it by one end in your hand, hold it perpen- 
dicularly, and it will bend so that it is hard to 
realize that it is not going to break into pieces. 
The reason for this is that the rock was once what 
is called a feldspathic quartzite ; but water, perco- 
lating through it, dissolved out it the alkaline 
substance, leaving the clayey matter. Thus the 
grains composing the stones are no longer held 
firmly together ; it is loose-jointed, as one might 
say. It is found only on the surface of sandstone 
deposits, and is of no use in building. In Brazil 
this sort of rock is the matrix in which diamonds 
are found. 
Speaking of diamonds reminds me that the stu- 
dents of the subject have found in South Africa 
for the flrst time a substantial clue to the processes 
by which precious stones were formed. Everyone 
knows that the diamond is pure carbon; but, 
albeit carbon is cheap enough, it has been found 
impossible to crystallize it profitably by artifice, 
though Professors Maskelyne and Cook have pro- 
duced very minute diamonds in the laboratory. 
Nature performs her chemical operations on a 
large scale and, of course, with superior facilities. 
The rocks at the South African mines are shales of 
a highly carbonaceous nature, and up through 
them has been forced in past times a great mass 
of eruptive rgck in a molten condition, so as to 
engulf the shale. - For a long time the mass 
remained slowly cooling, and incidentally to the 
process the carbon in the shale was crystallized 
out in the form of diamonds. Afterwards the rock 
decomposed and rotted away — for rock will rot 
like anything else — forming the blue clay from 
which the diamonds .are dug today. 
+♦* 
Three Chaldean monuments of antiquariiin value 
were recently discovered under the foundation of 
an old London house. The site was formerly oc- 
cupied by the dwelling of a Dutch merchant who 
traded in Persian ports. At the time of the great 
fire the stones probalily fell through the ruins by 
their weight, and escaped notice when the house 
was rebuilt. They belong to the pre-Semitic .age, 
and the characters upon them are of the most af- 
cliaic form. 
