26 POPULAR SCIENCE MONTHLY 



stirred up, thus filling the air with all sorts of impurities, irritating 

 and disease-bearing. The stuffy atmosphere one notices when entering 

 certain assembly halls and churches is nearly always due to lack of 

 energy or method in cleaning, quite often through inaccessibility in 

 * dirt corners ' or other hygienic fault in the design of buildings. 



The combustion of gas and kerosene in living rooms rapidly vitiates 

 the air. Each burner will use up as much oxygen as several persons, 

 besides generating heat, moisture and often sulphurous acid gas, spe- 

 cially injurious to nose and throat. Stoves or grates for heating or 

 cooking by gas should invariably be connected to a -flue to carry off the 

 products of combustion, Even if used for lighting only, the discharge 

 from lamps becomes very objectionable without ample provision for its 

 escape from the room. 



Smoke and vapors are unavoidable wherever cooking is going on, 

 but through immediate and effective removal at the starting point, 

 their spread can be prevented. There is no excuse for any odors in- 

 vading the living rooms; indeed, if the vapors are properly taken care 

 of, the air in the kitchen itself can be kept reasonably wholesome and 

 pure. 



Dust, smoke, gases or hot air from industrial sources which are 

 often allowed to contaminate the air in workshops and laboratories 

 can be classed as avoidable factors, since it is nearly always possible to 

 localize them. Grinding wheels, buffers or other machinery should be 

 equipped for this purpose with devices for mechanical suction to pick 

 up and remove the dust or fumes before they can spread and do harm. 

 Poisonous gases in laboratories should also be removed as soon as 

 generated. Waste heat which would otherwise become annoying should 

 be neutralized by insulation. The design of such arrangements re- 

 quires special training and experience, but the principles of it can 

 easily be understood and insisted upon by laymen. 



The Vitiation of the Air through Heating, Cooling and Ventilating 

 Apparatus. — Every one is familiar with the discomforts of modern 

 heating apparatus. The most frequent complaints are of dryness, 

 disagreeable odors or stuffy atmosphere, sometimes combined with over- 

 heating. These conditions are so common that they have almost come 

 to be regarded as unavoidable drawbacks, more or less peculiar to cer- 

 tain methods of heating. 



Since the capacity of air to absorb moisture increases with its tem- 

 perature, heating, by any method, will have a drying effect. In clear 

 cold weather, when the atmosphere out of doors contains little moisture, 

 the relative percentage indoors may drop below a point to which most 

 persons are acclimated. Unless made up by internal sources, some 

 artificial supply of moisture seems desirable in such cases. It is, how- 

 ever, not necessary and not desirable, as is often recommended, to go 



