CHEMICAL SCIENCE. 187 



following results were obtained from observations taken at fifteen 

 stations along a tidal river and its estuary. The stations varied in 

 height from three feet to six hundred feet, and in distance from the 

 river, from its bank to eight miles inland. Some of the stations were 

 in towns and villages ; from these we find that ozone, as a rule, in- 

 creases with increase of elevation and decreases with increase of dis- 

 tance from the river ; and that it is invariably in greater quantity in 

 the open country than in towns and villages. This, I believe, is a 

 universal law. It is the same on the Alps as at lower elevations. 

 The following results I obtained from observations forwarded to me 

 by a member of the Alpine Club. The observations were taken at 

 elevations varying from 740 to 8000 feet. The mean daily quantity 

 of ozone from 740 to 2000 feet is 15 ; from 2000 to 4000, it is 33 ; 

 from 4000 to 8000, it is 77. (The degree of humidity at the lowest 

 elevation was 58 ; at the next, 83 ; and at the last, 83 also.) Ozone 

 is a highly oxidized body, and it is easily decomposed by oxidable 

 substances. If a test-paper prepared with iodide of potassium be 

 freely exposed to the air in a locality where the quantity of these 

 substances is at a minimum, it will in time become deeply colored 

 brown, and ozone will be said to be at its maximum. If a similar 

 paper be placed in a locality where the quantity of oxidable substan- 

 ces is at a maximum, as over or in the neighborhood of drains and 

 cesspools, the paper will remain uncolored, and ozone will be at its 

 minimum ; and if the slip that becomes brown be placed in the latter 

 place, it will lose its color. In the first condition the ozone oxidizes 

 the potassium and sets the iodine free. In the second, the ozonized 

 air meets with incompletely oxidized substances, which are more easily 

 oxidable than the potassium; and in the third instance the brown 

 color of the paper is removed by sulphuretted hydrogen. The ocean, 

 with the wind that blows over it, is represented by the first condition, 

 and the land, with its wind bearing the products of combustion and 

 putrefaction, by the second and third conditions. The conditions of 

 an ozone period are undoubtedly those of the south or equatorial or 

 ocean current of the atmosphere, and those of a no-ozone period are as 

 clearly those of the north or polar or land current. With the former 

 we have low readings of the barometer, with the maximum of its 

 range and oscillations, increasing mean-daily and dew-point temper- 

 ature, maximum of rain, prevalence of cirri, halos, and high winds, 

 with negative electricity ; with the latter we have high readings of 

 the barometer, minimum of range and oscillations, decreasing tem- 

 perature, no halos, no cirri, low winds, settled weather, and positive 

 electricity. The atmospheric conditions, with ozone and those with no- 

 ozone, are so invariable, and ozone periods so frequently commence 

 and terminate with south-east and north-west winds, that the points 

 of the compass might not inaptly be arranged into four sets, namely, 

 the equatorial or ozone points, the polar or no-ozone points, and the 

 transition points the south-east, or the points of transition from the 

 north or polar to the south or equatorial, and the north-west, or 

 points of change from the latter to the former. In a medico-meteoro- 

 logical sense, I am not prepared to state that atmospheric ozone pro- 

 duces any form of disease, but I have no hesitation in saying that it 

 prevents diseases of the epidemic character, by removing their causes. 



