Chemistry / by George Wilson.

  • George Wilson
Date:
1857
Catalogue details

Licence: Public Domain Mark

Credit: Chemistry / by George Wilson. Source: Wellcome Collection.

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    cubic inches of hydrogen would leave the tube for each cubic inch of oxygen that entered it. These numbers—namely, 4 in the case of hydrogen, and 1 in that of oxygen—are inversely as the square roots of the densities of these gases, for oxygen is exactly sixteen times heavier than hydrogen, or their rela- tive densities are as 16 (0) to 1 (H), whilst the square root of 16 is 4, and that of 1 is 1. If the gases replaced each other in volumes, which were as the square roots of their densities, we should have four cubic inches of oxygen entering the stuccoed cylinder for one of hydrogen that left it; and the water, if originally standing at some height within the cylinder, would descend instead of ascending-. Exactly the reverse of this we have seen to be the case. It is the hydrogen which gives four cubic inches, whilst the oxygen returns only one. Or the replacing volumes are not as, but inversely as, the square roots of their densities. 418. It is the same with other gases, so that it can be announced, as a general law, that the diffusion-volumes of gases—that is, the volumes in which they replace each other— are inversely as the square roots of the densities of the gases. If this particular law be forgotten, the more general one may be remembered, that when light and heavy gases are ex- changing places, a larger volume of the light gas passes in the one direction than of the heavy gas in the other. 419. The spread of infectious diseases, the ventilation of apartments, the maintenance of animal respiration, and other important natural and artificial processes, are controlled by the law of gaseous diffusion, which belongs more strictly to physics than to chemistry, but cannot be omitted from any treatise on the latter. COMPOUNDS OP NITROGEN AND OXYGEN. 420. Nitrogen forms several important compounds both with oxygen and hydrogen. Those containing the latter element will be discussed along with the fixed alkalies. Three of the oxides (of which altogether there are five, see page 36) —namely, nitric acid, nitrous oxide, and nitric oxide—are important substances, and possess striking properties. The remaining two—hyponitrous and nitrous acids—are less in- teresting bodies:— Nitric Acid. Synonyme, Azotic acid; symbol, NO5; equivalent, 54. 421. This acid has been known from an early period, and still retains, as one of its titles, the appellation of aquafortis,
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