Lighting

"T HE crudest method of lighting I have ever seen is to be found in certain out-of-the-way corners of our mountain districts. Under the mantel of an immense fireplace there stands, on one side, a box of salt, kept dry by the heat of the fire, while on the other projects a large flat stone on which in the evening, with true economy, resinous splinters from the trunk of a fir-tree are burnt; and that is the only light, the only lamp, in the dwelling. By the light of this red and smoky flame the housewife prepares the soup and pours it into the porringers for the family returned from their labor in the fields, while the grandmother, silent in her big arm-chair, plies the spindle with her lean fingers."

"A common oil-lamp," said Claire, "would be far preferable to that little fire of resinous wood."

"I do not deny it," replied Uncle Paul; "but oil costs money, and a few little splinters of fir cost nothing."

"But that pitch-pine torch only gives light right round the fireplace. For going at night from one room to the next some other kind of light is needed."

"They have the iron lamp, in which a cotton wick inserted in a sort of socket burns grudgingly a few drops of nut oil."

"That must give a very poor light—not so good as a candle, even the kind that makes such a horrid smell."

"What are those bad-smelling candles made of, Uncle Paul?" asked Emile.

"They are made of either mutton or beef fat, which we know by the name of the tallow."

"There are others, of a beautiful white, that are not greasy to the touch and have hardly any smell."

"Those are tapers, or wax-candles, as they are called, and they are far superior to common candles, although made from the same material, tallow. It is true that the tallow destined for tapers undergoes thorough purification, which removes its disagreeable odor and its oil. The first step in this process is the boiling of the tallow in water to which lime has been added. Next there is called into service a powerful drug, oil of vitriol, which takes away the lime as soon as it has acted sufficiently. Finally the material under treatment is subjected to strong pressure which squeezes out and gets rid of the oily ingredient. After passing through these various stages the tallow is no longer what it was. It has no smell, or hardly any; its consistency is firm, its color a perfect white. In this new state, which is very different from the first, it is no longer called tallow but stearin.

"The notable improvement I have just described, which was destined to give us the odorless taper with its white flame in place of the foul-smelling, smoky tallow-candle, dates from the year 1831.

"Tapers, or wax-candles, are made in molds, which are of metal and open at their base into a common reservoir the use of which I will explain presently. Through each mold, running from end to end, passes a wick, which is fastened at the bottom by a small wooden pin, and at the top by a knot that rests on the little central opening of a conical cap. After the molds have been placed in position, with their pointed ends downward and their bases upward, the melted stearin is poured into the reservoir, whence it runs into the several molds. Nothing more remains to be done except to bleach and polish the candles. They are bleached by exposure to the sunlight for some time, and polished by rubbing with a piece of cloth.

"Oil, which I will speak of in detail later, is also used for lighting. There are several inferior kinds commanding so low a price as to permit of their use. Those in most common demand for lighting are rape-seed oil, colza oil, and nut oil. They are burned by the use of a woven cotton wick which soaks up the liquid at its lower end and brings it drop by drop to the flame.

"If the candle is allowed to burn fully exposed to the air, with no protecting glass chimney to regulate and increase the draft, the flame is dim and smoky, a part of the oil, decomposed by the heat, being lost in smoke or collecting in the form of snuff on the incandescent part of the wick. To burn this smoke, this carbon, and thus obtain a brighter light, a good draft must be generated, as in fireplaces and stoves, so as to utilize to the full the fuel that feeds the flame. This is attained by means of a glass chimney enclosing and surmounting the flame, allowing cold air to enter at the bottom and hot air to escape at the top. Only on this condition do lamps, of whatever sort, give a good light."

"I thought," said Marie, "that lamp-chimneys were only to protect the flame from puffs of air."

"Chimneys do indeed protect the flame from puffs of air that might make it flicker and go out, but they also fill another office no less useful: they generate a draft without which combustion would be imperfect and the light dim. If you remove the chimney you will notice that the flame immediately becomes smoky and dim; put the chimney on again, and the flame will instantly recover its vigor and clearness. It is the same with the lamp as with the stove: without a sufficiently long pipe to create a draft, or, in other words, to draw in air to the very heart of the fuel, the stove would burn badly and give out little heat; and without the glass chimney bringing to the wick a continual stream of fresh air the lamp would make but poor use of its oil supply and would give only a faint light.

"The chimney is especially indispensable with lamps that burn kerosene, a liquid very much used at the present time for lighting. The lamp hanging from the ceiling of this room to give us light in the evening is filled with kerosene. You must have noticed the great difference it makes with the lighted wick whether the chimney is on or off."

"That difference has always struck me," Marie replied. "Before the chimney is on the flame is red, very smoky, and gives hardly any light; but as soon as the chimney is put on, the smoke disappears and the flame turns a very bright white. Without its chimney the lamp would not give much light and would fill the room with black smoke."

"In kerosene lamps the air necessary for combustion comes through a number of little holes in the metal disk that supports the chimney. If these holes become obstructed with the carbonized refuse of the wick, the draft works badly and the lamp smokes. Then sometimes, ignorant of this detail, you are lost in conjecture as to the cause of the wretched light you are getting. The wick is badly trimmed, you say to yourself, it is too long or too short, there is not enough oil, or there is too much. You try this and that remedy, all to no purpose; the lamp still smokes. The right remedy is nevertheless very simple: it is only to take off the metal disk through which the wick runs, and with a brush thoroughly to clean the little holes with which it is riddled. These openings clean, the air once more comes freely to the flame, a draft is created without any obstacle, and the lamp burns as brightly as ever."