Chemistry : general, medical, and pharmaceutical including the chemistry of the British pharmacopoeia a manual on the science of chemistry, and its applications in medicine and pharmacy / by John Attfield ; edited by Leonard Dobbin.

  • Dobbin Leonard.
Date:
1903
Catalogue details

Licence: In copyright

Credit: Chemistry : general, medical, and pharmaceutical including the chemistry of the British pharmacopoeia a manual on the science of chemistry, and its applications in medicine and pharmacy / by John Attfield ; edited by Leonard Dobbin. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    has now liquefied it in large quantities, and has also obtained it in the solid condition. Obviously oxygen is not very soluble in water, or it could not be collected by the aid of that liquid. It is soluble, however, to a certain extent, about 3 volumes dissolving in 100 of water at ordinary temperatures. When any ordinary sample of cistern or river water is heated, or subjected to greatly reduced pressure, numerous small bubbles of gas, containing a considerable proportion of oxygen, gradually escape from it. The presence of dissolved oxygen in river and sea water is essential for the respiration of fishes. To observe the relation of oxygen to combustion, remove one of tlie tubes from the water, by placing the thumb over its mouth, and apply for a second a lighted wood match to the orifice ; the gas will be found to be incom- bustible. Extinguish the flame of the match, and then quickly introduce the still incandescent carbonised extremity of the wood well inside the test-tube ; the wood will at once burst into flame, owing to the extreme violence with which oxygen supports combustion. These tests of the presence of free oxygen may also be applied at the extremity of the delivery-tube whilst the gas is being evolved. (It is desirable to retain two tubes of the gas for use in sub- sequent experiments; also one tube in which only one- third of the water has been displaced by oxygen.) Rc/alion ol Oxygen lo Animat and Vegetable Life.—Not only the carbon at the end of a piece of charred wood, but any other substance that will burn in air (which, as will be seen presently, is diluted oxygen) will burn more brilliantly in pure oxygen. The warmth of the bodies of animals is kept up by the continuous burning of the tissues in the oxygen of the air, drawn into the system through the lungs. The pro- duct of this combustion is exhaled into the air as a gaseous compound of carbon and oxygen termed carbonic anhydride, a gas which, in sunlight, is absorbed by and decomposed in the cells of plants with fixation of the carbon and liberation of the oxygen. Thus, too, is the atmosphere kept constant in composition.