A treatise on chemistry. Vol. III, The chemistry of the hydrocarbons and their derivatives, or, Organic chemistry. Part I / by H.E. Roscoe & C. Schorlemmer.

Henry Enfield Roscoe

Date:: 1881

Credit: A treatise on chemistry. Vol. III, The chemistry of the hydrocarbons and their derivatives, or, Organic chemistry. Part I / by H.E. Roscoe & C. Schorlemmer. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

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$has to be burnt, or one which, on heating, gives olf large quantities of combustible vapours, the column of oxide must be longer than in other cases. The tube is then laid flat on the table and gently tapped, so that a free passage for the pro- ducts of combustion is left above the surface of the copper oxide. Inasmuch as copper oxide is a very hygroscopic substance and may, therefore, have absorbed moisture from the air during the process of mixing, this moisture must be removed when an exact determination of the hj'drogen is required. For this purpose the tube, prepared in the way described, is placed in connection with the exhausting syringe (p. Fig. 8), the second opening of which is joined to a U-tube (t) containing chloride of calcium. The combustion-tube {ah) is warmed in a water-bath or sand- bath, then exhausted, and dry air allowed to enter, and this operation repeated several times. 43 In order to avoid this tedious dessicating process, the sub- stance may, according to Bunsen's proposal, be mixed Avith the FiCi. 11. 1^1,; ]._). oxide of copper in the tube itself Tiiis is effected by means of a copper- or brass-wire bent at the end like a corkscrew (Fig. 9), a vertical and, at the same time, a rotatory motion being given to the wire. The tube is then placed in the combustion-furnace,$