Part 19

CANDLE OR FIRE CRACKERS.

Provide a number of little glass bulbs, put into each a drop of water, and seal it up; if it be then put into the flame of a candle, or the fire, the heat will soon convert the water into steam, and cause the bulb to burst with a loud report.

STEAM FROM THE KETTLE.

Observe attentively the steam that escapes from the spout of a tea-kettle, at the moment the water begins to boil, and you will perceive the steam to be condensed in minute drops on the interior edges of the spout. A few moments afterwards, provided the water continue to boil, the spout of the kettle will become perfectly dry; and, at the same time, close to it, there will be a certain space, say from one-half to three-fourths of an inch, throughout which not a particle of steam will be perceptible. This may be easily explained. When the water in the kettle begins to boil, the spout being cooler than the steam issuing from it, a portion of that steam is condensed. As more steam escapes, the metal soon becomes as hot as the steam, will no longer condense it, and the spout becomes dry. By this time the steam will displace the air immediately opposite the orifice of the spout, whence it will issue dry and invisible. As it is cooled by mixing with the surrounding air, it assumes its well-known cloudy appearance.

FIRE, WATER, AND AIR.

COLOURED FLAMES.

A VARIETY of rays of light is exhibited by coloured flames, which are not to be seen in white light. Thus, pure hydrogen gas will burn with a blue flame, in which many of the rays of light are wanting. The flame of an oil-lamp contains most of the rays which are wanting in sunlight. Alcohol, mixed with water, when heated or burned, affords a flame with no other rays but yellow. The following salts, if finely powdered, and introduced into the exterior flame of a candle, or into the wick of a spirit-lamp will communicate to flame their peculiar colours:

Muriate of Soda (common salt) Yellow. Muriate of Potash Pale violet. Muriate of Lime Brick red. Muriate of Strontia Bright crimson. Muriate of Lithia Red. Muriate of Baryta Pale apple-green. Muriate of Copper Bluish green. Borax Green.

Or, either of the above salts may be mixed with spirit of wine, as directed for Red Fire.

YELLOW FLAME.

Burn spirits of wine on common table salt or saltpetre.

ORANGE-COLOURED FLAME.

Burn spirit of wine on chloride of calcium, a substance obtained by evaporating muriate of lime to dryness.

EMERALD GREEN FLAME.

Burn spirit of wine on a little powdered nitrate of copper.

INSTANTANEOUS FLAME.

Heat together potassium and sulphur, and they will instantly burn very vividly.

Heat a little nitre in a fire-shovel, sprinkle on it flour of sulphur, and it will instantly burn. If iron filings be thrown upon red-hot nitre, they will detonate and burn.

Pound, separately, equal parts of chlorate of potash and lump sugar; mix them, and put upon a plate a small quantity; dip a thread into sulphuric acid, touch the powder with it, and it will burst into a brilliant flame.

Or, put a few grains of chlorate of potash into a table-spoonful of spirit of wine; add one or two drops of sulphuric acid, and the whole will burst into a beautiful flame.

THE CUP OF FLAME.

Put a little newly calcined magnesia into a tea-cup upon the hearth or hob, and suddenly pour in as much concentrated sulphuric acid as will cover the magnesia; in an instant, sparks will be thrown out, and the mixture will become completely ignited. To prevent accidents, the phial containing the sulphuric acid should be tied to the end of a long stick.

TO COOL FLAME BY METAL.

Encircle the very small flame of a lamp with a cold iron wire, which will instantly cause its extinction.

PROOF THAT FLAME IS HOLLOW.

Pour some spirit of wine into a watch-glass, and inflame it; place a straw across this flame, and it will only be ignited and charred at the outer edge; the middle of the straw will be uninjured, for there is no ignited matter in the centre of the flame.

Or, introduce into the middle of the flame one end of a glass tube, when the vapour will rise through it, and may be lighted at the other end of the tube.

CAMPHOR SUBLIMED BY FLAME.