An introduction to pharmaceutical chemistry / by John Attfield.

  • Attfield, John, 1835-1911.
Date:
1867
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to pharmaceutical chemistry / by John Attfield. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    end. It is made of thin glass, in order that it may be rapidly heated or cooled without risk of fracture. Heat chlorate of potassium (say, as much as will lie on a shil- ling) in a test-tube, by means of a spirit- or gas-flame ; gaseous oxygen is quickly evolved. Before applying heat, however, pro- vision should be made for collecting the gas. Collection of Gases.—Procure a piece of glass tubing about the thickness of a quill pen, and a foot or eighteen inches long, and fit it accurately to the test-tube by means of a cork. The tube is fixed in the cork through a round hole made by the aid of a rat-tail file. Setting aside the test-tube for a few minutes, pro- ceed to bend the long piece of tubing to the most convenient shape for collecting the gas. To hend Glass Tubes.—Hold the part of the tube required to b% bent in any gas or spirit-flame (a fish-tail gas-jet answers very well), constantly rotating it, so that about an inch of the glass becomes heated. It will soon be felt to soften, and will now, yielding to the gentle pressure of the fingers, assume any required angle. In the present case, the tube should be heated at about four inches from one extremity, and bent to an angle of about 90 degrees. Source of heat.—The source of heat for the test-tube may be the flame of an ordinary spirit-lamp, or, still better where coal- gas is procurable, a mixture of the latter with air. The simple flame of a common argand gas-burner is preferred by some ope- rators, especially when the usual glass chimney is replaced by a metal one about four or five inches long. If a piece, or cap, of wire gauze be fixed on to the top of the metal chimney, then the unlit gas which issues from the jets of the argand-burner becomes mixed with air inside the chimney, and the mixture when lit on the outer side of the gauze, burns with a flame as smoke- less and as little coloured as that of a spirit-lamp. Gas-lamps especially constructed to burn a mixture of coal-gas and air are sold by chemical-apparatus manufacturers.