Text-book of medical and pharmaceutical chemistry / by Elias H. Bartley.

  • Bartley, Elias Hudson, 1849-1937.
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: Text-book of medical and pharmaceutical chemistry / by Elias H. Bartley. Source: Wellcome Collection.

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    again expands on being reconverted into ordinary oxygen. This shows that it is a condensed form of oxygen. Ozone is times heavier than oxygen, and its molecule is represented by q^^q or Os. Tests.—The presence of ozone in the air may be detected by its action upon a paper saturated with a solution of potassium iodide and starch paste. This paper becomes blue by its action, owing to the liberation of iodine, which gives a blue color with starch. A piece of reddened litmus paper saturated with potassium iodide also becomes blue. A paper moistened with an alcoholic solution of guaiacum is also changed to a light blue by its action. A piece of paper im- pregnated with a solution of manganous sulphate or lead hydrate turns dark brown or black by its presence. These reactions disappear when the air is heated to 2600 C. (5000 F.). Ozone is found in the air, especially after thunder-storms, and when in appreciable quan- tities acts as a purifier of the air, destroying, by its oxidizing action, many forms of organized germs hurtful to animal and vegetable life. On this account it has been regarded as a valuable antiseptic and disinfectant. As it is very irritating to the mucous membranes, and when present to any considerable extent causes distressing coryza, or even hemoptysis, it is to be recommended with caution. Hydrogen and Oxygen.—Two compounds of these elements are known : Hydrogen oxide, or water, H20. Hydrogen peroxide, or hydrogen dioxide, H202. Hydrogen Oxide, or Water. Formula, H20. Molecular Weight, 17.88 (H = 1). Occurrence.—Water is so widely distributed in nature that it is almost universal. It exists in the three states : solid, liquid, and gas or vapor. It occurs in the solid form below the temperature of o° C. (320 F.), and as a liquid between o° C. (320 F.) and ioo° C. (2120 F.), and as a vapor above ioo° C. (2120 F.). In the form of vapor it exists in the air at ordinary temperatures. It is poured into it from combustion in various manufacturing processes, from volcanoes, by spontaneous evaporation from the surface of the ground, bodies of water, and the leaves of plants. Seven-eighths of the entire human body is water. Potatoes contain 75 per cent.; watermelons, 94 per cent. ; and cucumbers, 97 per cent. It enters into the com-