104 



SCIENCE. 



ATMOSPHERIC OZONE FOR JANUARY, 1881. 

 By L. P. Gratacap. 



The memorable discovery of Ozone by Schonbein, in 

 1840, bequeathed to the scientific world one of its ques- 

 ticnes vexata;, about which opinions and experiments 

 seem to have been equally at variance. As regards its 

 constitution and essential nature there seems little reason 

 to doubt it is a condensed form of oxygen, according to 

 the views of Andrews and Tait, and that it displays the 

 characteristic properties of that gas in an intensified de- 

 gree. Its existence in the air can be hardly less ques- 

 tioned, but the extent and origin of its presence are in- 

 volved in obscurity, and partly from the modifying influ- 

 ence of local circumstances and the identity of its 

 reactions with oiher atmospheric bodies the conclusions 

 of various experimenters are either equivocal or contra- 

 dictory. The fact that chlorine, sulphurous fumes, the 

 nitrogen oxides, affect the test papers in the same man- 

 ner as ozone, and that humidity of the atmosphere, 

 strong winds, bright sunshine, or local nuisances exag- 

 gerate or diminish the normal reaction, renders it difficult 

 to eliminate the error introduced by their adventitious 

 influence. The results here given were obtained with 

 test papers of starch and iodide of calcium, prepared, 

 presumably, like those of Dr. Mcffat, from starch and 

 iodide of potassium, and compared, after the test, with a 

 scale of eclors similar to Negretti and Zambra's. 



After E. Schone's recent condemnation of ozone tests 

 made in this way, they may appear valueless, but it 

 would hardly seem, admitting the justice of Schone's 

 strictures, that their comparative showing would be seri- 

 ously impaired. The coloration obtained was in a great 

 measure due to ozone, and its increase or decrease was 

 due in the same proportion to an increase or decrease of 

 this re-agent ; the contemporaneous influence of nitrogen 

 oxides may have deepened the tints, it certainly could 

 not have neutralized them, and inasmuch as the papers 

 were kept moist the effects of the varying humidity of 

 the air were, in a measure, cancelled. Precautions 

 against the disturbing influence of winds and that of 

 strong sunshine were also taken. Duplicate observa- 

 tions were taken at 10 feet and at 40 feet from the 

 ground, and their average (though in nearly all cases 

 they proved identical one with the others) recorded, as 

 the color-mark of the hours they were exposed. 



Observations were taken every 12 hours, dividing 

 the 24 between day and night, and notes kept of the 

 weather. As a rule, the papers exposed at an elevation 

 were more deeply colored than those near the ground, 

 though this was probably due to a freer circulation of 

 air. The papers at the periods of strongest ozonization 

 were changed throughout ; at other times they were 

 marked in spots and near the edges, showing an unequal 

 sensitiveness to the re-agents. In supplementary trials 

 on the effect of the wind, it was found that those papers 

 exposed to the wind were sometimes one-third deeper in 

 tint than the protected ones, and reached their maximum 

 much quicker. These contrasts were, of course, les- 

 sened with a diminished velocity of wind. 



The manifestations of ozone followed, as a rule, low- 

 ered barometric pressure and rising temperature, in other 

 words, they were coincident with change of weather. 

 This is an interesting confirmation of Houzeau's experi- 

 ments, and in the attempt I make below to give this a 

 graphic demonstration this generalization appears, i. e„ 

 that a wave of ozonization follows the storm wave, lag- 

 ging somewhat behind it, and appreciably corresponding 

 in duration and intensity to the force and continuance of 

 the air wave which preceded it.* In this connection it 

 will be noticed that threatening weather on the 1 6th and 

 1 8th was followed by a sudden projection of the ozone 



* As regards the sensible effects of the ozone following by many hours 

 the opening of the storm cn the yth and 13th, the reactions appeared con- 

 currently with a change in the weather from snow to rain. On th- other 

 hajad,the storm of the 21st opened with rain. 



curve which as rapidly subsides, indicating either atmos- 

 pheric disturbances responsive to an incipient but unfin- 

 ished change of weather, or else undulations of ozoniza- 

 tion coming from some neighboring storm centre or both. 

 Further on the curve of ozonization rises somewhat 

 before that of the weather, and I apprehend this may 

 often or always happen when storms of unusual severity 

 and violence are about to traverse a district. The thrill 

 of ozonization recorded on the papers taken in on the 

 morning of the 20th were prophetic of the fierce and 

 extraordinary tempest which devastated New York and 

 its vicinity upon the 21st. 



The high readings from the 25th to 29th accompanied 

 the advent of a cold wave in the Hudson River Valley 

 on the night of the 24th, which sent the mercury down 

 to 15" below o : at Poughkeepsie and brought colder 

 weather to New York and its vicinity, lasting four days, 

 with strong N.-W. and W. winds. This appears anal- 

 ogous to the strong ozonization concurrent with storms, 

 etc.; the atmospheric disturbance originating the cold 

 wave propagated an ozone wave which appears simul- 

 taneously with the former. It is not probably due simply 

 to an apparent increase of normal ozone from the rapid 

 passage of air currents past the tester. This latter effect 



j is doubtless efficient in heightening the entire result, but 

 the wind appears to act as an ozone carrier, bringing into 

 one area supplies of this gas formed in a different and 

 removed one. Indeed it does not appear unwise to spec- 

 ulate upon the possibility ot the wind acting as an ozone 

 generator since the irruption of a volume of air at a high 

 velocity of different temperature and density from that of 

 the points over which its path sweeps, must comprise 

 electrical changes, discharges and perturbations. Such 

 effects would correspond in their intensity with the viol- 

 ence and character of the air blast, and we might find 

 the neighboring areas to the track of a cyclone strongly 

 ozonized. As a matter of observation the strong ozoni- 

 zation on the 29th succeeded the strong winds which 

 ushered in the cold of the 27th and 28th. And in any 

 case the deeper tints during wind indicate justly enough 

 the increased prevalence of ozone in the areas swept 

 over by the gale. That wind is not always efficient in 

 changing the ozone papers was shown in Daremberg's 

 experience at Mentone, where, although variations were 

 caused by the wind, in some instances along the sea 

 board the coloration did not at all respond to the strength 

 of the former, and Houzeau is of the opinion that dry 

 winds have slight influence upon the papers. 



The cold wave was followed on the 30th by a still 

 snow storm, the shower of pellets falling through an 

 atmosphere unmoved by even a current of air. Threat- 

 ening weather succeeded the cessation of the snowfall 

 only to usher in the fierce storm of February 1st, when 

 snow, wind, and a low temperature united to arrest life 

 and motion upon the thoroughfares of land and water. 

 The ozone curve responds but feebly to these meterologi- 



j cal perturbations until February 1st, when it slowly rises, 

 recalling Houzeau's conjectures as to storms which gen- 



j erated ozone and storms which did not. 



It may seem superfluous, if not trivial, to record any 

 observations upon atmospheric ozone when the whole sub- 

 ject is involved in a fog of scientific confusion, contempt 

 and obloquy. It may be said that these observations 

 presented no inconsistent, aberrant or contradictory re- 

 sults, and that to the general student of our local mete- 

 reology they may in this graphic form exhibit some 

 features of interest. The chart is simply suggestive and 

 absolutely artificial ; the numbers on the left of the lines 

 indicate degrees of coloration and the weather line is de- 

 termined by three points : clear, threatening and stormy. 

 The readings were made at West Brighton, Staten 

 Island, in New York Harbor, the maxima of colorations, 

 and hence ozone, considered as coincident with the time 

 at which the reading was taken, 7.30, night and morning, 

 which must be at times barely approximative. 



