862 
The Exhalation of Ozone by Odorous Plants. 
[September, 
tests were applied as in the experiments on growing plants, with 
results as follows: 
No. experiment, Schoenbein.| Guaiacum. Ses 
im open air 
tC Ay SPR ..| marked slight very slight 
PEL se marked i 
Oe TIE. i dis $e es = 
i es T slight slight marked k 
a A eee negative | negative 4 xa 
Litmus 
(ved). 
negative 
‘6 
: State o 
Time. Rai? 
ghours| clear 
10 ce “ 
9 (Li “ce 
io ce ce 
9 “cc c6 
After three days the pine branches turned brown and the leaves 
rapidly dropped off. These facts doubtless account for negative 
results after the fourth day. It should be stated that we contin- 
ued to test them on the sixth and seventh days respectively, and 
with negative results in both of the latter instances. We were, 
however, encouraged by the success attending the first three 
experiments, and resolved to make another trial of pine branches: 
Accordingly we again selected a half dozen pine branches which 
moderately filled our little floral chamber, and allowed them to 
remain only until they began to show a change in color, which 
change was first observed at the end of the third experiment. 
The following results speak for themselves: 
$ : ; Schoenbein| Litmus : State of 
E CS: oe ae OE in open air.| (red). Time. | weather. 
gd fade ..| marked | marked | marked | negative 2 hours| clear 
No. “i essre r slight negative X s |clear, part- 
! ly clou 
Pith. Uoan = s slight as 190. * lear 
We also made four daily experiments with branches taken from 
the Norway spruce (Adies canadensis) and, as shown by the fol- 
lowing record, with happy results : 
ee aa z . Schoenbein| Litmus ; State of 
No. experiment. Schoenbein.| Guaiacum.\- “et air | (red). Time. | soegther. 
No.1.........| marked | marked slight | negative |12 hours| clear 
No. moon ao slight | negative au a a p 
No: Tse, civic} -Slight marked w a 
No. ossee) Marked slight marked X TaN 
We, unfortunately, were unable at that time to obtain more 
foliage of the same character, and thus our investigations were 
brought to an end. Although a greater number of experiments 
upor fhis point could have been desired, when, on the one hand, 
d how great and numerous the difficulties connected 
