* 858 The Exhalation of Ozone by Odorous Plants. (September, 
THE EXHALATION OF OZONE BY ODOROUS 
PLANTS. 
BY DRS. J. M. ANDERS AND G. B. M. MILLER, 
A the AmeERIcAN Naturauist for April and May of the year 
1884, there appeared two articles, by one of us, treating of the 
“ Exhalation of Ozone by Flowering Plants.” The reader will 
there find recorded the results of numerous experiments which 
were made with the view of ascertaining whether or not plants 
have the power to generate ozone. The chief conclusions there- 
from deduced were as follows: 1. That flowering plants in gen- 
eral are capable of generating ozone, and odoriferous flowers in 
particular. 2. That foliage plants do not possess this function. 
It should be remarked that the present re-investigation of the 
subject was undertaken with the view either of confirming or dis- 
proving the correctness of the above conclusions. Owing to the 
high importance of the question of the relation of plant growth 
to the generation of ozone, this course was deemed almost 
incumbent, 
As the more important properties of ozone were discussed in 
the previous papers, it is not deemed necessary to do so here. 
The hygienic relations of this substance also received brief atten- 
tion while its tests received careful consideration ; hence to fur- 
ther enlarge upon these phases of our subject, at present writing, 
would be a work of supererogation, The methods employed in 
the former experiments were likewise used in the present series. 
The following apparatus was used: A glass case large enough to 
contain a dozen or more thrifty growing plants in pots. Its 
dimensions were, length three and a half feet, width two and 
a half feet, and height two and a half feet. A portion of the 
top was left removable, so as to furnish an aperture through 
which the plants could be placed in the case and again taken out. 
The tests employed were the Schoenbein paper and paper im- 
pregnated with tincture of guaiacum. When exposed to ozone 7 
artificially prepared the Schoenbein paper turns quite blue, while 
__ the guaiacum paper first turns greenish-blue and finally a bright 
blue. In the present experiments we also employed the same 
_ terminology, viz., “marked,” “slight” and “very slight,” to 
_ denote the degree of blue coloration. 
— A dozen thrifty plants belonging to the species Coleus lumei, 
