Active oxygen.—Hydrogen Dioxide.

The peculiar odor of ozone explains the name given it by its discoverer, Schönbein, who long maintained alone the genuineness of this form of oxygen. It is now agreed by chemists that it is an allotropic modification of oxygen, in which three atoms are condensed into two.

The medical properties of ozone have been most successfully studied by Binz. It is an active oxygen, a powerful oxidizing agent, and therefore is so destructive as to be dangerous to handle. The tissues of the human body are affected by it in a peculiar manner. It sets up an acute catarrh of the respiratory mucous membrane if breathed in quantity. The coagulability of albumen is de-stroyed by it. It has been asserted that it causes pneumonia under certain unknown conditions.

Binz finds that ozone is a cerebral sedative, that it induces drowsiness and stupor; but this must be secondary to a primary stimulant effect, and may be due to changes in the protoplasm, on which it acts with great energy.