The carbon and hydro-carbons in fuel will not burn or unite with oxygen and produce rapid combustion except at a very high temperature, - that is, when made very hot. The temperature at which this union takes place is called the burning-point. This varies in different substances, and special means must be employed to produce it.

Some substances, like the phosphorus on matches, will burn very easily when heated by friction. The phosphorus ignites the sulphur, and the burning sulphur makes the wood hot enough to burn, and thus we have a little fire. If we hold the burning match near large pieces of hard wood or coal it will not make them burn, because the match will burn out before they are hot enough to take fire. But if we place paper or shavings and a pile of small pieces of soft wood under the hard wood, and apply the lighted match to the paper, we soon have a bright flame. The burning shavings heat and kindle the soft wood ; this in turn kindles the hard wood and coal; and in this way we make our fires.

The wood or coal will burn until they are nearly consumed, if they have the proper supply of air. The air, entering from beneath, should have room to circulate freely through the entire mass of wood or coal. There should also be a way for the smoke and products of combustion to escape freely.

In wood and coal there is a small amount of mineral matter. It will not burn, and in the process of combustion it is left as ashes. These settle under the fire, and, if allowed to accumulate, hinder the burning.

A fire for cooking purposes is best made in an iron box, or, as it is usually called, a stove, or range. By so doing we confine the heated air within a certain space, and can obtain more or less heat, as may be required. By means of a pipe we connect the stove with a chim- ney having an opening into the outer air. The ashes drop through a grate in the bottom of the fire-box into the pan beneath. We control the amount of heat obtained from the fire by dampers in the stove and pipe. These increase or diminish the supply of fresh air, regulate the circulation of hot air through the flues of the stove, and afford an outlet for the imperfectly burned carbon and products of combustion.

Through ignorant or careless management of a fire, much fuel is wasted, health is impaired, and not seldom human lives are sacrificed. Charcoal and anthracite coal should not be burned in close rooms, especially in open stoves, with the pipe dampers closed, or where there is a poor draught in the chimney. Poisonous gases are formed, which if inhaled cause death by suffocation. It is, therefore, a matter of vital importance that we so regulate our fires and ventilate our rooms that the air may not be impregnated with these deadly gases.