EFFECTS OF RESPIRATION. 



Although in large public buildings which are habitually thus 

 filled, proper means of ventilation are often provided, this is not 

 the case in general in private residences, where such assemblies 

 are only occasional. Hence it happens that large parties, balls, 

 and other social entertainments given in private houses are 

 extremely injurious to the health. Multitudes are crowded 

 together in brilliantly-lighted rooms. The respiration, the 

 exhalation from the skin produced by an elevated temperature 

 and by the exercise of dancing, and the combustion of vast 

 numbers of candles, lamps, and gas-lights, evolve carbonic acid in 

 large quantities, which, having no means of escape, accumulates 

 until the company becomes painfully sensible of its ill-effects on 

 respiration. Relief is then sought by opening one or more 

 windows or doors, by which currents of fresh air are let in, and 

 the foul air drawn out. If the air thus admitted were of a proper 

 temperature, this palliative of the evil might be admitted to be 

 partially efficient ; but the air thus introduced is usually of a 

 temperature from twenty to forty degrees lower than that of the 

 room. The persons exposed to these sudden cold currents, more 

 especially females, having their highly heated skins and open 

 pores extensively uncovered, receive a chill, by which the integu- 

 ment contracting drives back into the blood the fluids which ought 

 to have been permitted to escape by cuticular transpiration. 

 Hence arise numberless diseases, rheumatisms, colds, fevers, and 

 in more cases than is ever known or acknowledged, premature 

 and ultimate death. 



35. It will be apparent from these considerations how much it 

 behoves architects, builders, and proprietors to provide proper 

 expedients in the erection of private residences for the efficient 

 ventilation of rooms. 



36. We have stated that air is colourless and transparent, and 

 this is practically true not only of common air, but of gases 

 generally, when they are exhibited in such moderate quantities as 

 are usually submitted to observation or experiment. Strictly 

 speaking, however, air is not absolutely transparent or absolutely 

 free from colour. 



When a fluid is very faintly coloured, its peculiar hue is only 

 perceptible when a considerable depth or thickness of it is sub- 

 mitted to view. If a tapering glass, such as those used for 

 champagne, be filled with pale sherry or other liquor of a like 

 colour, the peculiar colour of the liquid will be distinctly enough 

 perceived at the top of the glass, when the eye views a certain 

 thickness of it ; but the colour becomes fainter and fainter 

 towards the point of the cone, where it is scarcely perceptible. 

 If a glass tube of small bore be dipped in the liquid, and, the 



15 



