Oxygen itself is not directly applicable as a germicide. In nature it undoubtedly plays an important part in general disinfection.

Ozone, O3, as a gas has a feeble germicidal action. Wyssoko-witsch has shown that in a percentage of 20-30 miligrams to the 100 cubic meters it has a restraining action on the development of many bacteria. Ozone, according to the researches of Ransome and Fullerton, has no particular action on the vitality of the tubercle bacillus.

Ozone developed in water by electrical means has some bactericidal action, but it is highly doubtful if it is a practical method for water disinfection, the results of Schroeder and Proskauer1 notwithstanding.

Among the most useful of the oxidizing agents are the peroxides of hydrogen, and a number of recently introduced organic peroxides under the trade names of acetozone, alphazone, etc.

Aqua Hydrog nii Dixidi - quae Hydrognii Dix-idiSolution of Hydrogen Dioxide. V. S. P.

Origin. - A slightly acid, aqueous solution of hydrogen dioxide, which should contain, when freshly prepared, about 3 per cent, by weight of absolute hydrogen dioxide, corresponding to about 10 volumes of available oxygen.

Description and Properties. - A colorless liquid, without odor, slightly acidulous to the taste, and producing a peculiar sensation and a soapy froth in the mouth; liable to deteriorate with age or by exposure to heat or protracted agitation.

Dose. - 1-4 fluidrams (3.7-15.0 Cc), well diluted with water [1 fluidram (4 Cc), U. S. P.].

Physiological Action. - Externally and Locally. - Applied to the skin it decomposes, but without much effect save in strong solution, when it irritates.

Applied to mucous membranes hydrogen peroxide is decomposed and oxygen is given off in large quantities. The oxygen given off is nascent and oxidizes surrounding substances very energetically. Applied to wounds or open surfaces the oxygen is given off in very large quantities.

In the stomach large quantities are also evolved, causing distention of the stomach in some instances. It is usually broken down completely before reaching the intestines.

Injected hypodermically oxygen is liberated, and if a bloodvessel is entered emboli of oxygen may form and it may thus cause death. Intravenous injection causes gas emboli and death.

The catalytic activity of the various organs after death varies considerably.

Therapeutics. - Externally and Locally. - Hydrogen dioxide is extensively employed to cleanse diseased surfaces, such as ulcers, buboes, fistulous tracts, etc. It has been highly recommended as an antiseptic in abdominal surgery. As an antiseptic wash in empyema, cystitis, joint-cavities, venereal sores, puerperal septic endometritis, etc., hydrogen dioxide is an exceedingly valuable agent.

Hydrogen dioxide appears to be an efficient injection in gonorrhea, and is much used as an antiseptic in many diseases of the eye, ear, nose and throat. It has been highly recommended as an application for diphtheritic membrane, although when frequently applied to the throat it causes an unpleasant sensation of dryness. It is highly valuable in tonsillitis. It is to be recommended for loosening up necrotic tissue wherever applicable.

Hydrogen dioxide serves a useful purpose in disinfecting drinking-water when suspected of pollution, 1 part sufficing for 1000 parts of water, in which amount the taste or other potable qualities of the water are in no way impaired.

Internally it has no important actions yet carefully studied. It may prove of some value in gastro-intestinal affections, and its use in the rectum, where the gas may be absorbed, is said to be of value by some clinicians.

Administration. - For external and local use the drug may be gargled, sprayed, or applied with a syringe or a swab, either in full strength or diluted with water. Whether for external or internal use, the solution should be freshly prepared; when given internally it should be taken from a porcelain or china, not a metal, cup or spoon.