Human physiology / by William Furneaux.

  • William Samuel Furneaux
Date:
1909
Catalogue details

Licence: In copyright

Credit: Human physiology / by William Furneaux. Source: Wellcome Collection.

    88/270 page 76
    Nitrogen, forming about 2-5 per cent, of the weight. Calcium „ „ 13 Phosphorus „ 1-2 „ „ Sulphur „ „ 15 Sodium, chlorine, flicorme, potassium, iron, magnesium, and silicon are also present in small quantities. Each of these is present in combination with others, thus giving rise to a variety of chemical compounds; but oxygen, nitrogen, and hydrogen also exist in small proportions in the elementary form as gases. Thus we see that the body is made up of a number of chemical compounds, each compound being formed by the union of two or more elements. These compounds are the proximate principles which enter into the formation of the various tissues of the body. Before proceeding to describe the chief compounds of the body, we will study the general characters of its four chief elements, viz. oxygen, carbon, hydrogen, and nitrogen. The simple experiment described above is sufficient to illustrate the chief characteristics of oxygen. It is an invisible gas, which powerfully supports combustion or burning, but is not itself com- bustible. O.xygen forms about one-fifth of the volume of the atmo- sphere, and is that constituent of the air which supports combustion and animal life. It also forms eight-ninths of the weight of water, and is so abundant in the earth’s crust that it is calculated to form more than one-third the weight of the whole globe. Carbon is a solid element which is capable of existing in a variety of forms. As a natural mineral substance we are familiar with it in two forms—black lead {plumbago or graphite') and the diamond; the latter being its purest and crystalline form. Charcoal and lamp-black are artificial varieties of carbon. When carbon burns, it combines with the oxygen of the air, forming an invisible compound gas, called carbonic acid gas. This gas is also produced by the combustion of any compound substance which contains the element carbon, such as coal, coal gas, wood, oils, spirits, &:c. (See page 78.) In order to ascertain the chief properties of hydrogen gas, it will be advisable to resort to a few simple experiments:— {a). Fit any kind of bottle with a good cork, through which passes a straight glass tube ; and see that the apparatus is air-tight with the exception of the tube through which the gas has to pass. Put into the bottle a few scraps of zinc, and cover these with diluted sulphuric acid (about eight parts of water to one of the strong acid). Hydrogen gas immediately begins to come off, and, being lighter than air, may be collected in an inverted bottle. {b). Collect some of the gas in a dry bottle as above described, and then hold the mouth of the bottle near a flame, taking great care that no fiame is brought near the apparatus in which the gas is being generated. The hydrogen
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