30 
POPULAB SCIENCE BE VIEW. 
gaseous substance possessing a peculiar odour : it is a nega- 
tive word, conveying no accurate idea of the composition of 
the substance — and perhaps this is an advantage to science 
rather than the contrary, at least for the present time; the word, 
that is to say, is meaningless, and might, from its derivation 
“ o£w, to smell,” apply to any gas that is odorous ; but because 
it is meaningless as a definition, it pledges itself to no theory or 
hypothesis as to the elementary constitution of the substance 
it designates. When that constitution is discovered, and all 
chemists shake hands over it in cordial agreement, it will be 
good time to change the name, if that be desirable, and make 
the designation define the substance as it really is in its 
essence. 
The circumstances under which Ozone may be presented are, 
to a considerable extent, known. When an electrical machine 
— a common frictional machine — is set in motion, and sparks 
or flashes are taken from the positive conductor, Ozone is 
developed, and its characteristic odour is readily detected. 
When water is decomposed by electricity, Ozone appears, with 
oxygen, at the positive pole ; in fact, according to one view, 
the oxygen is simply in an active state, ozonized. If oxygen, 
nitrous oxide gas, or carbonic acid gas, be placed in a glass 
jar, and electrical sparks be passed through the gas. Ozone is 
developed, and the same has been stated in respect to nitrogen, 
but Dr. Wood and I were unable by experiment to sustain 
this last assertion. Ozone may also be obtained by heating 
one end of a glass rod gently, and then immersing the said 
end in a jar through which rectified ether is diffused in vapour. 
A ready way of making Ozone is to take sticks of common 
phosphorus, scrape them until they have a metallic lustre, place 
them, in this condition, in a large bell jar, and half cover them 
with water. Tbe air in the bell jar is soon charged with 
Ozone, and a large room can readily be supplied with air in 
the ozonized state by this process. 
To make Ozone on a large scale an apparatus invented by 
Siemens is the best. A cylinder of glass is covered neatly on 
its outer surface with tinfoil in the same manner as a Leyden 
jar. Then within this cylinder a smaller cylinder, also coated 
with tinfoil, is introduced and fixed with cork. The two free 
ends of the large cylinder are closed with corks well coated 
with sealing-wax varnish, and each cork is perforated so that 
a small wooden or glass tube may be inserted. There is thus 
formed a chamber of glass, lined with tinfoil, and if a bellows 
be attached to one of the small tubes, and air be driven from 
the bellows, it passes through this chamber and can be collected 
as it escapes at the opposite end. To ozonize the air that may 
be sent through this chamber, it is now only necessary to 
