Academy of Science. 



most probable and abundant source of Ozone to our atmosphere. This hypothesis, 

 too, enables us to explain certain well known facts in vegetable nutrition otherwise 

 inexplicable. Thus we know tliat "many plants which contain the greatest amount 

 of nitrogen in their composition are not always those which are most benefited by 

 the use of nitrogenous fertilizers. Such plants are almost invariably large-leaved, 

 exposing an immense foliage surface. Hence the query naturally arises whether 

 these plants may not have the power of supplying themselves with nitrogen com- 

 pounds through the indirect action of the Ozone exhaled from their foliage. We 

 know that this element has the power of oxidizing the nitrogen of the atmosphere 

 first into nitrous and then into nitric acids, which in combination with the atmos- 

 pheric ammonia might thus be furnished the plant in no insignificant quantit}^ 



But from whatever source produced, it is obvious tiiat by far the larger portion 

 of our atmospheric Ozone must, on account of its intense oxidizing powers, be 

 almost instantly consumed by decomposing organic matter wherever present. 

 Hence is explained the circumstances in which we find the most abundant evidence 

 of its existence. The atmosphere immediately surrounding stables or outhouses, or 

 over decaying refuse heaps will afford not the slightest trace of Ozone ; not, we are 

 to understand, that it may not be there produced, but, when formed, it is at once 

 consumed by the oxidizing processes in progress in such localities. Hence we are 

 not surprised to learn that in cities the indication of its presence are much more 

 feeble than in the pure air of the country uncorrupted by organic effluvia. Even in 

 :S0 moderately a populated citj^ as Manhattan, I have found the result of my Ozone 

 observations much legs striking than in the fresher atmosphere of College Hill, two 

 miles away. In the atmosphere of Topeka I have found its amount still less. In 

 densely populated, and especially in manufacturing cities, we of course find the 

 diminution more startling still. The city of Lyons, France, has positively' alforded 

 not a single indication of the presence of Ozone, and so proverbially is this the fact 

 that it has been dubbed among French chemists, "the town without Ozone." 



In comparing the results of diverse seasons also we very naturally find its quan- 

 tity in winter fully twice that in summer. This is accounted for not only by the 

 fact that in the winter season our electrical conditions are much more energetic and 

 intense, but more especially by the circumstance that the greater proportion of the 

 Ozone then produced in the atmosphere remains there undestroj^ed, the i)rocess of 

 oxidation being then nearly at a stand-still and the organic matter of the earth fre- 

 quently protected by a dejjosit of snow. For precisely similar reasons we find the 

 reaction for Ozone much stronger at night than during the day. The maximum 

 amount for the entire twenty-four hour^ is almost invariably just before sunrise; as 

 by the condensation of watery vapor always taking place at that time, the air is 

 freed from its organic impurities. But it is obvious that the amount of Ozone 

 which we can measure in our atmosphere affords not the least indication of the 

 amount which may have been produced there, for it is only jjossible for us to meas- 

 ure the residuum, that which remains undestroyed by oxidizable matter. 



It is to be seriously regretted tliat the methods for quantitative estimation of 

 Ozone sliould be so imperfect and so liable to grave error. Numerous methods for 

 such estimations have been devised, the greater proportion of them dependent upon 

 its well-known oxidizing power. It is well known that Iodide of Potassium is 

 perfectly unalterable in oxygen gas. Under the action of Ozone, however, it is 

 instantly decomposed, caustic potassa formed and free Iodine liberated. A test 

 paper has hence been constructed in which wine-red litmus paper is impregnated 

 with a solution of Potassium Iodide and exposed to the action of the Ozone of the 



