122 Scientific Intelligence. _ 
purer, exactly as if the azote retained in the tissues of the plant, or in the 
water, was gradually expelled by the oxygen. Similar experiments were 
; also, 
trogen. But, after all, he could not obtain any oxygen gas free from 
azote. 
Boussingault now devised a new method of proceeding, by which he 
avoided the difficulty about extraneous nitrogen, &e. e mean results 
of 25 experiments (which are detailed particularly i in the memoir), made 
with a variety of plants, are, that 100 measures of carbonic acid gas, 
decomposed by foliage under the light, gave 97:2 of oxygen gas; and 
that 1:11 of azote had appeared which, from the plan of the experiments, 
could not have come from the water, nor have been contained in the 
At this point Boussingault raised the question whether this gas, which 
remained after the oes of the oxygen by the pyrogallate and the 
carbonic acid by potassa, was Hreeegiok and really nitrogen. A suite of 
experiments, devised ante cuted in this view, brought out the interest- 
ing see that the sensi poser which, moreover, corresponded ve 
n the amount of oxygen gas that had disappeared, was oxyd of 
So « foliage during the decomposition of carbonic acid does not 
composed by flings in the air? 
Boussingault concludes his paper with the remark, that the earlier 
observers looked at their discoveries rather from the hygienic than the 
= point of view; that, while Priestly announced his brilliant 
discovery by the statement that plants purify the air vitiated by combus- 
tion or a the respiration 7 animals, = is curious enough that a century 
afterwards it should come to be demonstrated, before the Academy of 
Sciences, that probably ae leaves of ‘al plants, i certainly those of 
aquatic plants, while emitting oxygen gas which ameliorates the atmos 
phere, also emit one of the most deleterious of known gases, carboni¢ 
oxyd! He closes with the pregnant and natural query, whether the un 
healthiness of marshy districts is not attributable, at least in part, to 
We add, that what strikes us with most surprise, is to learn that if 
these results are true, the vegetable machinery would seem to work at & 
loss, and with a real, though it be a small, waste i material! When 
any carbonic acid taken into the leaves es passes off unchanged, so much 
work is not done; but there is no waste or loss in the e process of manu- 
But, looking at the food of plants and their preduets,—compat 
ing the raw material with the manfactured article,—it seems apparent 
