26 THE CULTURE OF FARM CROPS. 



ancient poet realized through some inspiration this fact as 

 yet then unknown, and put it into a form of life and per- 

 sonality. The spark is the sunbeam ; which indeed starts- 

 dead matter into life and fills the earth with vitality ; caus- 

 ing the luxuriant vegetation which in turn supports directly 

 and indirectly every form of animal life. The sunbeam is- 

 then the master spirit of the universe ; controlling the great 

 agent of destruction and building up again the structures 

 which oxygen reduces to dust. 



OZONE. 



This subject is too important to leave without a reference 

 to a form of oxygen which plays a most important part in 

 nature and is believed to have some effect upon vegetation. 

 This is called ozone. When an electrical spark is passed 

 through dry air a peculiar odor is perceived. The cause of 

 this was not understood until recently when Prof. Schonbien 

 proved that it was a form of oxygen greatly increased in 

 intensity. It is believed by some chemists that ozone (as it 

 was termed by its discoverer because of its peculiar odor) is 

 formed by the combination of two atoms of oxygen with 

 each other; or in other words, an oxide of oxygen. This 

 substance is therefore of great intensity, equal in force to 

 that of oxygen multiplied by itself. It has an extraordinary 

 energy and produces changes which oxygen is unable to do. 

 It corrodes silver, bleaches colors untouched by oxygen, 

 destroys the odor of tainted flesh instantly, by decomposing 

 the gases which escape from it, and causes the decay of woody 

 fiber with excessive rapidity. It is believed to be the cause 

 of the mysterious souring of milk in dairies which so often 

 occurs after thunder storms, when the peculiar odor of ozone 

 pervades the air. The vivid greenness of the herbage of the 

 meadows after thunder showers is also supposed to be due 

 to the effects of the ozone produced and washed into the soil 

 by the rain. 



This substance is readily detected by means of slips of 

 test paper made by soaking them in a mixture of iodide of 

 potassium dissolved in water, and starch. The ozone frees 



