64 HO-\V CROPS FEED. 



several times its weight of air or oxygen.* It is entirely 

 insoluble in water. It has, when breathed, an irritating 

 action on the lungs, and excites coughing like chlorine gas. 

 Small animals are shortly destroyed in an atmosphere 

 charged with it. It is itself instantly destroyed by a heat 

 considerably below that of redness. 



The special character of ozone that is of interest in 

 connection with questions of agriculture is its oxidizing 

 power. Silver is a metal which totally refuses to combine 

 ^^itii oxygen under ordinary circumstances, as shown by 

 its maintaining its brilliancy without symptom of rust or 

 tarnisli when exposed to piire air at common or at greatly 

 elevated temperatures. When a slip of moistened silver 

 is placed in a vessel the air of which is charged with 

 ozone, the metal after no long time becomes coated with a 

 black crust, and at the same time the ozone disappears. 



By the application of a gentle heat to the blackened 

 silver, ordinary oxygen gas., having the properties already 

 mentioned as belonging to this element, escapes, and the 

 slip recovers its original silvery color. The black crust is 

 in fact an oxide of silver (AgO,) which readily suffers de- 

 composition by heat. In a similar manner iron, copper, 

 lead, and other metals, are rapidly oxidized. 



A variety of vegetable pi<2;meuts, such as iiidiijo, litmus, etc., are 

 speedily hleaclied by ozone. This action, also, is simply one of oxidation. 



Gorup-Besanez {Ann. Ch. u. /%., 110,86; also, rhysiologische Vfiemie) 

 has examined the deportment of a number of orsxanic bodies towards 

 ozone. He finds that egg-albumin and casein of milk are rapidly altered 

 by it, while flesh fibrin is unaffected. 



Starch, the sugars, the organic acids, and fats, are, when ]nirc, unaf- 

 fected by ozone. In presence of (dissolved in) alkalies, however, they 

 are oxidized with more or less rapidity. It is remarkable that oxidation 

 by ozone takes place only in the presence of water. Dvy substances are 

 unaffected by it. 



The peculiar deportment towards ozone of certain volatile oils will be 

 presently noticed. 



* Babo and Claus (Ann. Ch. v. Ph.. 2d Sup., p. 304) prepared a mixture of oxy- 

 gen and ozone coutaining nearly G per cent of the latter. 



