344 SCIENTIFIC RECREATIONS. 



From the foregoing observations it will be perceived how very desirable 

 it is that ventilation should be attended to. People close up windows and 

 doors and fireplaces, and go to bed and sleep. In the morning they com- 

 plain of headache and lassitude ; they wonder what is the matter, and why 

 the children are not well. Simply because they have been rebreathing 

 the carbonic acid. Go into a closed railway carriage which is nearly filled 

 (and it is astonishing to us how people can be so foolish as to close every 

 outlet), and you will recoil in disgust. These travellers shut the ventilators 

 and windows " because of the cold." A very small aperture will ventilate 

 a railway carriage ; but a close carriage is sickening and enervating, as 

 these kind of travellers find out by the time they reach their journey's end. 

 Air was given us to breathe at night as well as by day ; and though from 

 man's acts or omissions there may be circumstances in which " night " air 

 may affect the health, we maintain that air is no more injurious naturally 

 than " day " air. Colder it may be, but any air at night is " night " air, 

 in or out of doors at night ; and we are certain that night air in itself 

 never hurt any healthy person. It is not nature's plan to destroy, but to 

 save. If a person delicate in constitution gets hot, and comes out into a 

 colder atmosphere, and defy nature in that way, he (or she) must take the 

 consequences. But air and ventilation (not draught) are necessaries of 

 health, and to say they injure is to accuse nature falsely. There are many 

 impurities in the air in cities, and in country places sometimes, but such 

 impurities are owing to man's acts and omissions. With average sanitary 

 arrangements and appliances in a neighbourhood no one need be afraid to 

 breathe fresh air night or day ; and while many invalids have, we believe, 

 been retarded in recovery from being kept in a close room, hundreds will 

 be benefited by plenty of fresh air. We should not so insist upon these 

 plain and simple truths were there not so many individuals who think it 

 beneficial to close up every avenue by which air can enter, and who then 

 feel ill and out of spirits, blaming everything but their own short-sightedness 

 for the effect of their own acts. An inch or two of a window may be open at 

 night in a room, as the chimney register should be always fully up in bed- 

 rooms. When there are fires the draught supplies fresh air to the room with 

 sufficient rapidity. But many seaside journeys might be avoided if fresh air 

 were insisted on at home. 



There is another and an important constituent of the atmosphere called 

 OZONE, which is very superior oxygen, or oxygen in what is termed the 

 " Allotropic " state, and is distantly related to electricity, inasmuch as it can be 

 produced by an electrical discharge. This partly accounts for the freshness 

 in the air after a thunderstorm, for we are all conscious that the storm has 

 " cleared the air." The fresh, crisp ozone in the atmosphere is evident. 

 Ozone differs from oxygen in possessing taste and smell, and it is heavier 

 by one-half than the oxygen gas. There is a good deal of ozone in the sea 

 breeze, and we can, though not infallibly, detect its presence by test-papei 

 prepared with iodide of potassium, which, when ozone is present, will turn 



