Bubble

“ For as a bubble reflects whatever surrounds it, whether upon the banks, upon the stream, or clouds immeasurable overhead, illuminating with inward mysterious brightness their lights, shades, colours, and perspectives, so his nature as of other men took on the forms and colouring of his surroundings and like a bubble 86tinctured them with a radiance that came from within himself. ”

“ A soap bubble, black yet retaining all its changing lights and flashing reflections, is the nearest approach to a just description, and then there are to specify the rich, red eyes, eyes gleaming like polished gems. ”

“ The Colours of Bubbles with which Children play are various, and change their Situation variously, without any respect to any Confine or Shadow. If such a Bubble be cover'd with a concave Glass, to keep it from being agitated by any Wind or Motion of the Air, the Colours will slowly and regularly change their situation, even whilst the Eye and the Bubble, and all Bodies which emit any Light, or cast any Shadow, remain unmoved. ”

“ The movement of the water in itself exercises fascinations over a boy. There are always bubbles, based strongly in froth, sailing gallantly along.—One speculates how long a bubble will swim before it hits a rock, or is washed into nothing by an eddy, or is becalmed in a sheltered corner to ride at jaunty anchor with a navy of similar delicate tonnage. ”

“ In pushing a bubble through a ring smaller than itself, by means of a flat film on another ring, it is important that the bubble should not be too large; but a larger bubble can be pushed through than would be expected. It is not so easy to push it up as down because of the heavy drop of liquid, which it is difficult to completely drain away. ”

“ Did you not learn in our conversation of yesterday, that air has weight, and exerts a pressure as much upwards as downwards and laterally? Were this not the case, how could the air in the interior of our bodies counteract the pressure of the atmosphere? The form of the bubble proves the same fact in a different way; for, had the air in its cavity pressed more in any one direction than in another, the bubble could not have been round, or, to speak more correctly, a sphere. ”

“ The bubble is generally creased by the weight of the liquid along these channels. It must be remembered that the base of the bubble is in a state of oscillation, and that the whole is liable to burst at any moment, when such figures as 6 and 7 of the previous series will be seen.
SERIES V.
The Splash of a Drop, followed in detail by Instantaneous Illumination.
The Size of Drop and Height of Fall are the same as before, but the hollow shell (see figs. 4 and 5 of the previous Series) does not succeed in opening, but is left as a bubble on the surface. ”

“ The air inside a bubble is generally under pressure, which is produced by its elasticity and curvature. If the bubble would let the air pass through it from one side to the other of course it would soon shut up, as it did when a ring was hung upon one, and the film within the ring was broken. ”

“ Why is it so easy to blow bubbles with some liquids, and so hard to form them with others? Why does a bubble when blown at the end of an open tube gradually contract and disappear? Why, when it bursts, does it not still remain a liquid film, but is shattered to an almost imperceptible dust? ”

“ In knocking bubbles together to show that they do not touch, care must be taken to avoid letting either bubble meet any projection in the other, such as the wire ring, or a heavy drop of liquid. Either will instantly destroy the two bubbles. There is also a limit to the violence which may be used, which experience will soon indicate. ”

“ I hope that none of you are yet tired of playing with bubbles, because, as I hope we shall see during the week, there is more in a common bubble than those who have only played with them generally imagine. ”

“ With the bursting of each bubble, and the clearing of the scum from the surface of the red hot mass, the light begins, increases in intensity, and then as the scum again begins to collect on the surface, decreases, and finally disappears, and not until the bursting of the next bubble is it again visible. ”

“ The very simplest form of balloon is a soap-bubble. Most of us have probably at some time or other amused ourselves by blowing soap-bubbles, without perhaps troubling ourselves to understand the whys and wherefores of the case.
Why is it that a soap-bubble blown with air from the lungs ascends? You will tell me perhaps that it ascends because the air which comes from the lungs is of a lighter ‘nature’ than the atmosphere No, indeed, instead of having a lighter it has a heavier nature. ”

“ Why, because the water of which it is composed has an attraction of particle for particle:—so great, indeed, that it gives to this bubble the very power of an india-rubber ball; for you see, if I introduce one end of this glass tube into the bubble that it has the power of contracting so powerfully as to force enough air through the tube to blow out a light (fig. 22) —the light is blown out. And look! see how the bubble is disappearing, see how it is getting smaller and smaller. ”

“ We must now, however, pass on to another property of the surfaces of liquids, namely, that they press on the liquid, or air which they contain, in much the same way as a blown-out bladder presses on the air within it. I will show you an experiment illustrating this in the following way: If a bubble presses on the air within, then it is evident that, if we made a hole in its side, the tendency of the compressed air would be immediately to escape through the hole, and we should have a current of air flowing out of the bubble, which would thus become smaller. ”

“ This, therefore, is the excess of the pressure of the air within the bubble over that of the external air, and it is due to the action of the inner and outer surfaces of the bubble. We may conceive this pressure to arise from the tendency which the bubble has to contract, or in other words from the surface-tension of the bubble.
If to increase the area of the surface requires the expenditure 268 of work, the surface must resist extension, and if the bubble in contracting can do work, the surface must tend to contract. ”

“ Nine times out of ten you will succeed, and a [45] bubble will swell out from the spool as in Fig. 81. These wooden bubble-blowers last a long time, with no danger of breaking when accidentally dropped on the floor, and you can always find enough to provide one for each of the players who meet for a trial of skill in bubble-blowing.
Fig. 81—You can blow bubbles with a spool.
Now try
Pretty Butterflies
which fly from spools. Cut a butterfly (Fig. 82) from bright-colored tissue paper or thin writing paper, bend at the dotted line and paste on the large end of a very small cork. ”

“ How on earth do you know that that bubble comes from the wake of the House-boat?"
"By my chemical knowledge, merely," replied Holmes. "A merely worldly vessel leaves a phosphorescent bubble in its wake. That one we have just discovered is not so, but sulphurescent, if I may coin a word which it seems to me the English language is very much in need of. ”

“ I called one of the bubble forms, if you remember, by its name, catenoid; this is produced when there is no pressure. The dotted curve in the second figure B is this one; and to show that this catenary can be so drawn, I shall roll upon a straight edge a board made into the form of the corresponding section, which is called a parabola, and let the chalk at its focus draw its curve upon the black board. There is the curve, and it is as I said, exactly the curve that a chain makes when hung by its two ends. Now that a chain is so hung you see that it exactly lies over the chalk line. ”

“ It hadn't had to take the form of this terrible bubble. It might as easily have been a sudden sharp burst behind his eyes or a slower, subtler gnawing at his vitals. But he'd known it was coming, as every man knows and tries to forget it is coming. ”

“ This I have also often observed naturally performed by the heat of the Air, which being able to rarifie the upper parts of the Water sooner then the lower, by reason of its immediate contact, the heat of the Air has sometimes so slowly increased, that I have observed the Bubble to be some hours in passing between the top and bottom. ”

“ All round this bubble a vast number of bacteria collect in a thick, moving circle, but as soon as all the oxygen of the bubble has been absorbed they fall apparently lifeless, and are scattered by the movement of the liquid. ”

“ In other words, ale having a greater specific gravity than water, and also greater viscidity, the bubble formed has a thicker coating, and requires a longer time for its disrupture. Taking the round of all the 'frothy headings,' we find the same rule prevail. In the spray from the paddle of a steamboat, in the froth on the surface of beverages, in the sparkles on a cup of tea, the air is in the first place entangled among the particles of liquid, and thus forms bubbles in the struggle to escape. ”

“ A scientific friend observed to the author, that, as the globe possesses less surface than any other figure of equal capacity, it is of all forms that which is best calculated to allow the closest approximation of the particles of soap and water; and as there must exist amongst such particles a strong cohesive tendency, after having been forcibly stretched out, as it were, by the air blown into the bubble, it follows that, did no other cause operate, the bubble would assume the spherical form. ”

“ Now that there is a very small bubble, the pressure as measured by the water is about one quarter of an inch on the scale. The bubble is growing [Pg 57] and the pressure indicated by the water in the gauge is falling, until, when the bubble is double its former size, the pressure is only half what it was; and this is always true, the smaller the bubble the greater the pressure. As the film is always stretched with the same force, whatever size the bubble is, it is clear that the pressure inside can only depend upon the curvature of a bubble. ”

“ If you take a blown-up bladder under water and let go of it, it will fly up to the surface of the water and will swim on it. Just so, when water is boiled in a pot, it becomes light at the bottom, over the fire,—it is turned into a gas; and when a little of that water-gas is collected it goes up as a bubble. First comes up one bubble, then another, and when the whole water is heated, the bubbles come up without stopping. ”

“ When the bubbles are large, and when they follow each other rapidly, a continual effervescence is maintained upon the surface of the water. But if the size of the bubbles be reduced, or if the solvent capacity of the liquid be increased, the surface will become almost, if not quite, perfectly tranquil. ”

“ As the temperature increases these "beaded bubbles winking at the brim" give place to much larger bubbles, which are formed at the bottom of the vessel, and which rise a little way in the liquid, and then contract and disappear in a most mysterious manner, producing a hissing or simmering sound. But as the heating goes on, these bubbles, which consist of steam, rise higher and higher in the liquid, till at last they reach the surface and escape, producing a bubbling agitation, or the phenomena of ebullition. ”

“ Rough sphere falling 60 cm. Scale 3/4.
[pg 88] Thus the first three figures of Series VIII show the last moments of a bubble which has burst, spontaneously, and so has made way for the jet of Fig. 3. (These are taken from a splash into petroleum with 24·5 cm. fall.) But the last two figures, 4 and 5 (taken with a 32 cm. fall) , show how a bubble which might otherwise have been permanent, is stabbed by the rising jet and destroyed. With water and 60 cm. fall the jet appears sometimes to rise quite unimpeded, and sometimes to be checked by the still closed bubble. ”

“ The bubble, being very sensitive, responds to the sound movement in greater or less degree. As it vibrates, it naturally moves the quartz thread with it, and the moving shadow of the string is caught by the photographic film in the camera. ”

“ In like manner, although air does not manifestly attract air or water water in entire bodies, yet a bubble is more easily dissolved on the approach of another bubble than if that other bubble were away, by reason of the appetite of coition between water and water, and between air and air. Such Clandestine Instances (which, as I have said, are of the most signal use) exhibit themselves most conspicuously in small and subtle portions of bodies; the reason being that larger masses follow more general forms ”

“ But if a bubble be heated, and its parts brought to a larger sphere of attraction by the agitations from heat, it will no longer fall to powder when broken at its point. It may also have its parts ground away at pleasure, without falling to powder, because grinding agitates all the contiguous parts with strong vibrations, like heat, and enlarges the sphere of their attractions. ”