Chemistry / by George Wilson.

  • George Wilson
Date:
1857
Catalogue details

Licence: Public Domain Mark

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

    118/348 page 110
    stool of the pneumatic trough, or in a basin of water. The combustible is then to be kindled, and a jar full of air placed over it. If alcohol be employed, the car- bon and hydrogen which it contains rapidly unite with the oxygen of the confined air, and form carbonic acid and water, which are immediately dissolved by the liquid in which the jar stands. If the experiment be made properly, as soon as the alcohol ceases to burn, the water F!8- 36- begins to rise within the jar, and ascends till it occupies about one-fifth part of its capacity, replacing the oxygen, which has been converted into water and car- bonic acid. The gas which remains is the nitrogen of the air. Alcohol has this advantage over most combustibles, that it leaves the nitrogen colourless, but it frequently ceases to burn before the whole of the oxygen is withdrawn from the air. Phosphorus, accordingly, which removes every trace of oxygen, is generally preferred; but when it is made use of, the nitrogen must be allowed to stand over water till the phosphoric acid, which spreads through it in white fumes, has been absorbed by the water. 390. Properties.—Nitrogen is strikingly characterised by the absence of all positive properties. It has no taste, colour, or odour; no action upon colouring matter; it neither burns nor supports combustion; and it cannot maintain animal respiration. 391. The only experiment which can readily he tried with it is its action on flame. In relation to combustion, gases are divisible into three classes:—1. Those which support combustion, of which oxygen is the best ex- ample; 2. Those which are combustible, of which hydrogen is one; and 3. Those which neither burn nor support combustion, among which nitrogen ranks. A candle introduced into the gas (fig. 37) is at once extinguished without kindling the nitrogen. 392. In reality, however, nitrogen is combustible. This may be proved by mingling it with hydrogen, and kindling the mixture as it issues from a jet into the tent along with the hydrogen, so that whilst the latter combines with oxygen to form water, the former unites with the same gas to form nitric acid. Electric sparks or lightning discharges, when they pass through air,
    digitised image 1
    digitised image 2
    digitised image 3