Household Administration, Its Place in the Higher Education of Women

by Unknown

PHYSICAL SCIENCE IN THE HOUSEHOLD

We may for this purpose examine some of the laws of common physical and chemical phenomena, neglect of which has resulted in much needless discomfort in daily life, and even more serious consequences. For instance, the laws of expansion of gases and liquids with heat, and their subsequent behaviour, are phenomena that are often imperfectly realised. There is probably no person who is unacquainted with the law of gravitation, but there are many persons who accept literally the statements that smoke rises and that balloons ascend. A clear understanding of what actually takes place when gases and material masses appear to move in opposition to the law of gravitation is essential to any scheme for warming and ventilating the house.

A very simple experiment will serve to reconcile the apparent contradiction of the universal law by the observed fact. Suppose we have two fluids, oil and water, of which oil is, bulk for bulk, lighter than water. If the oil be poured into a glass beaker, it will be seen to rest at the bottom of the beaker; if water be now poured into the same 83 beaker the water will go to the bottom of the beaker and will displace the oil and lift it up so that the oil will float on the water; the oil may be lifted to any height we please if sufficient water be poured in to lift it to that height. If a single drop of oil be introduced into the water by means of a pipette and be liberated at the bottom of the beaker the water will close in under it, and lift it up to the surface. In both cases the oil “rises” through the water. Oil, however, has no tendency to “rise” by itself, and in this case it lay motionless until it was lifted by the heavier fluid. We may use colloquial language when describing phenomena if we bear in mind what is really taking place.

A balloon “rising” through the air is exactly analogous to the drop of oil in the water. The balloon is, bulk for bulk, lighter than air; the air therefore closes in under it and lifts it just as the water lifted the bubble of oil.