Practical papers—the Atmosphere. 369 
call the sky, or taking cognizance of the tint on the distant hills. 
There is air in water, yet not like that surrounding the earth. 
Water exposed to the atmosphere absorbs a much larger propor¬ 
tion of oxygen than of nitrogen, an arrangement by which fish 
obtain the requisite supply of oxygen from a small quantity of 
air. 
We now approach a branch of this subject comparatively new 
and exceedingly interesting to one desiring to penetrate nature's 
secrets. 
Two other gaseous substances pertaining to the atmosphere, 
which undoubtedly exert an important influence over animal ex¬ 
istence, remain to be examined. 
Pure oxygen undergoes a remarkable modification when sub¬ 
jected to a series of electric discharges. It acquires more active 
properties, emits a peculiar odor and effects oxidations beyond the 
power of ordinary oxygen. The peculiar odor, noticeable in the 
air after the passage of a lightning bolt, is due to the formation of 
this gas. Ozone is oxygen condensed ; three volumes of oxygen 
forming two volumes of ozone. It is absent from places densely 
populated and present in the pure country air. It is more abund¬ 
ant in winter than in summer, in cloudy than in clear weather, by 
night than by day, and is especially plentiful during a heavy fall 
of dew and in storms of snow. The bleaching qualities of new 
fallen snow are due to the presence of ozone. This gas is highly 
irritating to delicate lungs, and in large quantities may cause epi¬ 
demics of catarrh, colds and influenza. Notwithstanding, its gen¬ 
eral influence is probably beneficial to animal existence, as it oxi¬ 
dizes and destroys many volatile organic substances prejudicial to 
health, and thus by removing infectious matter from the air, ex¬ 
tirpate the germs of epidemic diseases. 
But the marvels of the air multiply. A gas concealed from 
man for ages calls vigorously for recognition, and willing or 
unwilling we are constrained to consider the claims of autozone. 
It seems to be produced simultaneously with ozone, and is like 
that, a modification of oxygen gas. It has even been discovered 
in the fiuor spar of bararia. The odor of autozone is exceedingly 
disagreeable, that of ozone merely pungent and irritating. Unlike 
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