78 
POPULAR SCIENCE REVIEW. 
4. These facts explain the conversion of legumine into asparagine. 
Asparagine in leguminous plants only disappears in plants exposed to the 
iglit. Pfeifer’s researches have shown that asparagine is poorer in carbon 
and hydrogen, and richer in oxygen than legumine and other proteic 
materials. The transformation of legumine into asparagine only takes 
place in the light, because this accelerates the absorption of oxygen, but 
his condition would not suffice if the carbonic acid exhaled were not less in 
quantity than the oxygen absorbed. A part of the oxygen, not represented 
n the exhaled carbonic acid, is probably fixed by the albuminoid principles 
during the formation of asparagine. — Comptes Rendus, 2 Qth October avid 22nd 
November , 1880. 
CHEMISTRY. 
The Liquefaction of Ozone and its Colour in the Gaseous State. — Ozone, 
such as one usually prepares, possesses so little tension in oxygen, at most 
53 mm., that the physical properties of this body are hardly known and dis- 
tinguished from those of oxygen. One knows the difficulties which Soret has 
so ably overcome in determining the density of ozone by operating on weakly 
ozonized oxygen. One of the fixed physical properties of this body is its 
heat of formation, which was accurately determined by Berthelot, in spite of 
the state of dilution in which it is found on leaving the apparatus for ozoni- 
zation. 
The preparation of a mixture, very rich in ozone, is then the first condi- 
tion to be fulfilled in order to acquire new notions of this curious body. 
Hautefeuille and Chappuis have already established the fact that the isomeric 
transformation of oxygen submitted to electricity, obeys simple laws, and 
that the proportion of ozone increases but very little with the pressure for 
every temperature ; whereas, in passing from 20° to — 55°, the proportion of 
ozone increases five-fold. Removed from the action of electrical discharges, 
the mixture of oxygen and ozone ceases to be a homogeneous and balanced 
system ; in spite of that, the mixture is preserved without appreciable altera- 
tion so long as a constant temperature is maintained, if we operate on it 
below 0°. This relative stability of ozone allows us to compress the mixture 
and to obtain the tensions of ozone of several atmospheres. 
As it is necessary to prepare ozone, destined for these experiments, under 
the strongest possible tension, one mu3t ozonize oxygen at a very low tempera- 
ture. Consequently the oxygen remains a quarter of an hour in an apparatus 
of alternating discharges, whose concentric tubes of thin glass are dipped 
into chloride of methyl; then one passes it into a test-tube, terminated by a 
capillary tube of the Cailletet apparatus. This reservoir, of about 60cc, at 
first empty and kept at — 23°, not being able to fill itself at one time under a 
pressure approaching 760 mm., is put rapidly in communication, five times 
successively, with the electric apparatus, the capacity of which cannot ex- 
ceed 20cc. In a quarter of an hour, one succeeds by this method in filling the 
test-tube with a mixture of oxygen and ozone, very fully charged with the 
latter gas. The test-tube is then taken away from the chloride of methyl 
and separated from the electric apparatus, and the gas which it contains is 
