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Free Books / Cooking / Boston School Kitchen / |  |
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Introductory |
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Free Books / Cooking / Boston School Kitchen / | |
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Introductory |
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This section is from the "Boston School Kitchen Text Book" book, by Mary J. Lincoln. Also available from Amazon: Boston school kitchen text-book.
In connection with the first and second lessons the pupils should learn about the four most important elements, namely, oxygen, nitrogen, hydrogen, and carbon.
Oxygen is a gas found as an element in the air and in combination everywhere. It is one fifth of the air, one half the solid crust of the earth, eight ninths of the water, about four fifths of the weight of vegetable bodies, and three fourths of the weight of animal bodies. It is the supporter of animal life; we are constantly taking it into our bodies and without it we should die. It sustains combustion and burns or unites with all other elements except fluorine. At a low temperature it unites slowly with iron, causing it to rust, and with wood, causing it to decay. It attacks all vegetable and animal substances and decomposes them, producing a form of oxidation or slow combustion. In every such chemical change heat is evolved, although it may not always be perceptible to our senses.
At a high temperature oxygen combines rapidly with some elements and produces fire or rapid combustion.
Nitrogen is a gas, and constitutes four fifths of atmospheric air. It is found in all vegetable substances, but chiefly in animal tissues. It forms about 26 per cent of the human body. It dilutes the air and thus makes combustion less furious than it would be in oxygen alone and renders the air mild and suitable for us to breathe.
Hydrogen is a gas, and is the lightest substance known.
It is seldom found free in nature, but its compounds are everywhere. Combined with oxygen it forms water. In this form it is found in all animal and vegetable substances. Pure hydrogen burns instantly in the air when lighted and produces intense heat, and the result of the burning is water-vapor.
Carbon is a solid elementary substance. Its combinations with other elements are in the form of liquids, gases, and solids.
It constitutes nearly one half of the weight of all dry vegetable and animal substances. It exists in a pure state in the diamond, and in a nearly pure state in charcoal and so-called black-lead or graphite. The charcoal that we burn, the graphite in our pencils, and the diamonds we wear are all different forms of the same element, carbon. The black mass left when bread is burned in the oven, or sugar on the stove, or fat in the frying-pan, is also carbon.
For further information the teacher is referred to " First Lessons on Minerals," by Mrs. Ellen II. Richards.
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