1866. | Chemistry. 263 
carbonic acid which held the lime in solution. In a paper entitled 
“ Chemical Researches on Vegetation, Functions of Leaves,” read 
before the French Academy on the 12th of February, M. Coren- 
winder says that he repeated the experiments of Ingenhousz on 
the leaves of aerial plants—that is to say, he exposed them to the 
sun in bell-glasses, filled with water from a spring, which held 
bicarbonate of lime in solution, and found that the leaves became 
covered with a deposit of pure carbonate of lime. M. Corenwinder 
has thus verified the fact which M. Gratiolet only suspected. In 
the same paper M. Corenwinder says that leaves coloured wholly or 
in part, white, yellow, or red, in consequence of exhaustion, must 
be distinguished from those leaves which are normally these colours 
when their vitality is in all its plenitude; that the former do not 
produce oxygen under the influence of the solar rays, whilst the 
latter give it forth in abundance. Buds and leaves just issuing 
from them give off carbonic acid even in sunlight, which, however, 
decreases as they develop themselves, the amount of oxygen con- 
tinually increasing until the leaves are adult and complete, when 
oxygen only is given off during the day. But if a plant is placed 
at a distance from a window in an apartment, or in a shady place, 
it gives off carbonic acid during the day, which varies in amount 
according to the nature of the plant and the feebleness of the light. 
This explains the difficulty experienced in preserving plants in an 
apartment. 
IV. CHEMISTRY. 
(Including the Proceedings of the Chemical Society.) 
A question of as much interest to Chemistry as to Meteorology 
has recently been discussed at the Academy of Sciences. Ii relates 
to the presence of ozone in the atmosphere; and it elicited the 
opinion of some of the most eminent French chemists that none of 
the tests im ordinary use can afford satisfactory evidence on the 
question. It was shown, indeed; by M. Frémy, that Schonbein’s 
paper is affected by many bodies likely to be present in the air ; by 
the oxides of nitrogen, by peroxide of hydrogen, by the acid pro- 
ducts of combustion, and by many other bodies, whose presence is 
not improbable. Further than this, the instability of ozone m the 
presence of organic matters and nitrogen, would lead to the con- 
clusion that it must be destroyed as soon as formed in the atmo- 
sphere. The one test which will prove conclusively the existence 
of ozone in the air, M. Frémy said he had tried many times without 
obtaining the faintest indications of its presence. As the question 
is of great interest, we state that the test on which M. Frémy 
relies, is the oxidation of silver by a current of moist air. With 
VOL. Ill. T 
