1884.) The Exhalation of Ozone by Flowering Plants. 471 
case, which was then accurately closed by the removable piece 
of glass already spoken of; the test papers having been moist- 
ened and tacked on the branches or stems of the plants. In 
the first series of experiments flowering plants were used, 
twelve in number, each having several flowers and about 
four square feet of leaf surface. They consisted of varieties 
of geraniums, fuchias, begonias, hydrangeas and petunias. 
Upon these plants eighteen observations were made of about 
four hours each, during the latter part of the month of May, 
1883 ; weather mostly fair. The Schoenbein showed “very 
slight 5 indications for seven of the experiments and one “ slight ” 
coloration, there being ten negative results. The guaiacum 
papers gave more striking results, the change in the papers being 
braaa for ten of the experiments and slight for the remaining 
s ie one which was negative. Great care was taken to 
ee re eh experimented with in a healthy condition; they 
a a eft in the pots in which they had been grown. There 
Seal a which can be assigned why the results in these 
ieee. = were not very striking with the iodized starch test 
rit ua Sir nents were of too short duration; and secondly 
opr s ucted indoors, for the air of the case was originally 
an. i room, and a portion at least of the ozone which 
oe en generated by the plants would have been de- 
eas he impurities of the air in the case. 
Pamoka nowledge of the very unfavorable conditions un- 
their ce experiments were: conducted, but encouraged by 
res ae success, it was resolved to make a trial of odorif- 
tle floral — under the same conditions. Again our lit- 
bushes. four of er was filled with plants, consisting of seven rose 
a. tation pinks, and six heliotropes. The duration 
elei ieo te about ten diurnal hours each; weather mostly 
“vey tS Re cloudy, With the Schoenbein test there were 
one well « “nee in most instances, two “slight” and 
iho can, ed,” while the guaiacum papers were “ marked” 
periments o ape being “ slight.” The number of ex- 
naturally that Seg These investigations suggested the idea 
Cori orous flowering plants might be better ozone 
nt inodorous ones. The external atmospheric 
ceding gg very similar during the time of both the pre- 
of experiments, the maximum temperature ranging 
