Chemistry and Physics. 233 
and pressure as unity. These plottings show (1) that up to 355° 
all t urves are contained in a single line parallel to the axis 
of abscissas, and the density is normal; with rising 
rature, so that under low tensions the density becomes constant 
peratures atomically as I;.and that the variations of density 
with temperature and pressure correspond to a progressive dis- 
sociation.— C. R., xcii, 39, Jan., 1881. G. F. B. 
. Researches upon Ozone.—HAvTEFEUILLE and CHAPPUIS 
have presented to the Chemical Society of Paris a valuable me- 
moir upon ozone. They first studied the effect of temperature 
lot. 
at 20°, 0°149 at 0° and 0-214 at —23°. Under 180 mm. pressure, 
the quantity was 0°089 at 20°, 0°137 at 0° and 07181 at —23°. 
Next the effect of mixture with other gases was investigated, 
and it was found that while at 0° no effect was observed, at —23° 
the amount of ozone was increased to 0°216 when the oxygen 
was mixed with four times its volume of nitrogen, and to 0°240 
when twice as much nitrogen was present. Hydrogen and sili- 
i tetrafluoride increase still more the quantity of ozone. e 
blue color in the tube, which de as the compression in- 
creased till under a pressure of several atmospheres, it becam 
Indigo-blue, ing the tube to —88° by immersion in liquid 
C th ; 
hyponitrous oxide, the color became three or four times darker, 
