Chemistry : general, medical, and pharmaceutical including the chemistry of the British Pharmacopœia a manual on the general principles of the science, and their applications in medicine and pharmacy / by John Attfield.

  • John Attfield
Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: Chemistry : general, medical, and pharmaceutical including the chemistry of the British Pharmacopœia a manual on the general principles of the science, and their applications in medicine and pharmacy / by John Attfield. Source: Wellcome Collection.

    32/850 page 8
    the moutli of the tube in it, be lifted out of the water and placed close by till wanted, the water remaining in the cup efFecttially preventing the gas from escaping. On the large scale, oxygen may be made in the same way, larger vessels (glass flasks or ii'on bottles) being employed. Less heat also will be necessary if the chlorate of potassium be previously mixed with very fine sand, or, still better, with about an equal weight of common black oxide of manganese. Note on the Collection and Storage of Gases.—It may be as well to state that nearly all gases, whether for experimental or practical purposes, are collected and stored in a similar manner. Even coal-gas is generated at gas-works in iron retorts very much the shape of test-tubes, only they are as many feet long as a test-tube is inches ; and the well-known gigantic gas-holders may be viewed as inverted iron test-tubes of great diameter. Properties.—Oxygen is a colourless gas. Cailletet and Pictet have succeeded in liquefying it. Obviously it is not very soluble in water, or it could not be collected by the aid of that liquid. Oxygen is soluble to a certain extent, however (about 3 volumes in 100, at common temperatures), or fishes could not breathe. Other noticeable features are its want of taste and smell. Next, to show the relation of oxygen to combustion, remove one of the tubes fi-om 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 incombustible. Extinguish the flame of the match, and then quickly introduce the still incandescent carbonaceous extremity of the wood half-way down 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 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 subsequent experiments; also one tube in
    digitised image 1
    digitised image 2
    digitised image 3