Part 22

MORE THAN FULL.

Fill a glass to the brim with water, and you may add to it spirit of wine without causing the water to overflow, as the spirit will enter into the pores of the water.

TO CAUSE WINE AND WATER TO CHANGE PLACES.

Fill a small narrow-necked bulb with port wine, or with water and coloured spirit of wine, and put the bulb into a tall, narrow glass jar, which is then to be filled up with cold water: immediately, the coloured fluid will issue from the bulb, and accumulate on the surface of the water in the jar, while colourless water will be seen accumulating at the bottom of the bulb. By close inspection, the descending current of the water may also be observed, and the coloured and the colourless liquids be seen to pass each other in the narrow neck of the bulb without mixing.

The whole of the coloured fluid will shortly have ascended, and the bulb will be entirely filled with clear water.

PYRAMID OF ALUM.

Put a lump of alum into a tumbler of water, and, as the alum dissolves, it will assume the shape of a pyramid. The cause of the alum decreasing in this peculiar form is briefly as follows: at first, the water dissolves the alum very fast, but as the alum becomes united with the water, the solvent power of the latter diminishes. The water, which combines first with the alum, becomes heavier by the union, and falls to the bottom of the glass; where it ceases to dissolve any more, although the water which it has displaced from the bottom has risen to the top of the glass, and is there acting upon the alum. When the solution has nearly terminated, if you closely examine the lump, you will find it covered with geometrical figures, cut out, as it were, in relief, upon the mass; showing, not only that the cohesion of the atoms of the alum resists the power of solution in the water, but that, in the present instance, it resists it more in some directions than in others. Indeed this experiment beautifully illustrates the opposite action of cohesion and repulsion.

VISIBLE VIBRATION.

Provide a glass goblet about two-thirds filled with coloured water, draw a fiddle-bow against its edge, and the surface of the water will exhibit a pleasing figure, composed of fans, four, six, or eight in number, dependent on the dimensions of the vessel, but chiefly on the pitch of the note produced.

Or, nearly fill a glass with water, draw the bow strongly against its edge, the water will be elevated and depressed; and, when the vibration has ceased, and the surface of the water has become tranquil, these elevations will be exhibited in the form of a curved line, passing round the interior surface of the glass, and above the surface of the water. If the action of the bow be strong, the water will be sprinkled on the inside of the glass, above the liquid surface, and this sprinkling will show the curved line very perfectly, as in the engraving. The water should be carefully poured, so that the glass above the liquid be preserved dry; the portion of the glass between the edge and the curved line, will then be seen partially sprinkled; but between the level of the water and the curved line, it will have become wholly wetted, thereby indicating the height to which the fluid has been thrown.

CHARCOAL IN SUGAR.

The elements of sugar are carbon and water, as may be proved by the following experiment: Put into a glass a table-spoonful of powdered sugar, and mix it into a thin paste with a little water, and rather more than its bulk of sulphuric acid; stir the mixture together, the sugar will soon blacken, froth up, and shoot like a cauliflower out of the glass: and, during the separation of the charcoal, a large quantity of steam will also be evolved.

FLOATING NEEDLES.

Fill a cup with water, gently lay on its surface small fine needles, and they will float.

WATER IN A SLING.

Half fill a mug with water, place it in a sling, and you may whirl it around you without spilling a drop; for the water tends more away from the centre of motion towards the bottom of the mug, than towards the earth by gravity.

ATTRACTION IN A GLASS OF WATER.

Pour water into a glass tumbler, perfectly dry, and it may be raised above the edge, in a convex form; because the particles of the water have more attraction for each other than for the dry glass; wet the edge, and they will be instantly attracted, and overflow, and the water will sink into a concave form.

TO PREVENT CORK FLOATING IN WATER.

Place at the bottom of a vessel of water, a piece of cork, so smoothly cut that no water gets between its lower surface and the surface of the bottom, when it will not rise, but remain fixed there, because it is pressed downward by the water from above, and there is no pressure from below to counter-balance it.

INSTANTANEOUS FREEZING.

During frosty weather, let a vessel be half filled with water, cover it closely, and place it in the open air, in a situation where it will not experience any commotion: it will thereby frequently acquire a degree of cold more intense than that of ice, without being frozen. If the vessel, however, be agitated ever so little, or receive even a slight blow, the water will immediately freeze with singular rapidity. The cause of this phenomenon is, that water does not congeal unless its particles unite together, and assume among themselves a new arrangement. The colder the water becomes, the nearer its particles approach each other; and the fluid which keeps it in fusion gradually escapes; but the shaking of the vessel destroys the equilibrium, and the particles fall one upon another, uniting in a mass of ice.

Or, provide a glass full of cold water, and let fall on its surface a few drops of sulphuret of carbon, which will instantly become covered with icy network: feathery branches will then dart from the sulphuret, the whole contents of the glass will become solidified, and the globules will exhibit all the colours of the rainbow.

TO FREEZE WATER WITH ETHER.

Fill a very thin glass tube with water. Close it at one end, and wrap muslin round it: then frequently immerse the tube in strong ether, allowing what the muslin soaks each time to evaporate, and in a short time the water will be frozen.

PRODUCTION OF NITRE.

Dip into the above solution a piece of paper: if its colour be changed to brown, a drop or two more acid must be cautiously applied: if, on the contrary, it reddens litmus paper, a small globule or two of potassium will be required; the object being to obtain a neutral solution: if it then be carefully evaporated to about half its bulk, and set aside, beautiful crystals will begin to form, which will be those of the nitrate of potash, commonly called nitre, or saltpetre.

CURIOUS TRANSPOSITION.