Lessons in elementary chemistry : inorganic and organic / by Henry E. Roscoe.

Date:
1867
Catalogue details

Licence: Public Domain Mark

Credit: Lessons in elementary chemistry : inorganic and organic / by Henry E. Roscoe. 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.

    35/422 (page 17)
    II.] from a small flask or boiler, passed over the red-hot metal through the tube ; hydrogen gas is given off, and oxide of iron left in the tube. The most convenient process of preparing pure hydrogen in quantity depends upon a property possessed by those metals, such as iron or zinc, which decompose water at a red heat, namely, that these metals are able to evolve hydrogen from water at the ordinary temperature of the air if a dilute acid be present. For the purpose of thus obtaining hydrogen, a flask or bottle is provided with a cork and tube as represented in Fig. 4, some zinc clippings are Fig. 4. introduced, and a mixture of one part of sulphuric acid and eight parts of water poured in through the tube funnel. After a few minutes a rapid effervescence com- mences, and the evolved gas is collected over water in bottles or cylinders as in the case of oxygen. Care must, however, be taken that all the air is expelled from the flask before the hydrogen is collected ; this is easily ascer- C