472 The Exhalation of Ozone by Flowering Plants, (May, 
from 85 to 88° Fahr. Repeated testing of the atmosphere of 
the room in which the case was situated gave no indications of 
the presence of ozone. 
The question now very naturally arose whether the colorations 
were due to ozone or to some of the substances which give 
same reactions with these papers; hence, further investigation was 
necessary in order to exclude, if possible, these interfering con- 
ditions, before it could be claimed for plants that they were capa- 
ble of emitting or converting the oxygen of the air into ozone, 
It was also deemed important to conduct future experiments out 
of doors as, for reasons already given, it was expected more de- 
cided results would be obtained. The case was removed to the 
back yard, which lies to the eastward of the dwelling: Here the 
plants received the sunlight for at least eight hours daily during 
clear weather, and the yard was of good size. In the first series 
of experiments in this locality the plants last named were ef 
ployed. 
After observations for seven consecutive days of clear weather 
the Schoenbein paper gave “ slight” reactions in four cases Ti 
“ marked” reactions in three. The guaiacum paper gave “slight 
indications in three and “ marked ” in four experiments. It wil 
be seen that these experiments gave more marked results the 
those made within doors. It may be stated that it was fo 
that the coloration of the Schoenbein or iodized starch test ¥ 
“ slight” instead of “ very slight” as indoors, and in three @* 
actually “ marked,” against one “ marked ” result in the preceding 
series. The guaiacum tests were nearly correspondingly of the 
marked. It is probable that the more surprising results © i 
last series are not attributable solely to the chan 
but also in some degree to the fact that the experimen 
longer duration. A piece of red litmus suspended 1n Pri 
during these experiments gave no indication of the yar l 
ammonia. Peroxides of hydrogen could not have been ape | 
actionary agent, since that substance is decomposed at ar l 
ture of 70° Fahr., while the temperature of the atmosphere r 
the case, which was carefully noted, was never found io 
Fahr. These observations were made during the first l 
June, 1883, the weather being very warm and the p externi ! 
of the air within the case being higher than that of perimet q 
air. Good reactions were, however, obtained in later € : 
