RESPIRATION. 137 



passages, the nostrils, to give as warning of approaching 

 harm. Take, as an example, the ordinary illuminating 

 gas of cities, from which so many accidents happen. How 

 many more deaths would it cause if, when a leak occurs, 

 we were not able to discover the escape of the gas by means 

 of its disagreeable odor. 



29. Organic matters exist in increased measure in the 

 expired breath of sick persons, and impart to it, at times, a 

 putrid odor. This is especially true in diseases which, 

 like typhus and scarlet fever, are referable to a blood 

 poison. In such cases the breath is one of the -means by 

 which nature seeks to expel the offending material from 

 the system. Hence, those who visit or administer to fever- 

 sick persons should obey the oft-repeated direction, " not 

 to take the breath of the sick." At such times, if ever, 

 fresh air is demanded, not alone for the sick, but as well 

 for those who are in attendance. 



30. Dust in the Air. Attention has lately been di- 

 rected to the dust, or haze, that marks the ray of sunshine 

 across a shaded room. Just as, many years ago, it was dis- 

 covered that myriads of animalcula infested much of the 

 water we drank, so now the microscope reveals "the gay 

 motes that dance along a sunbeam" to be, in part, com- 

 posed of multitudes of animal and vegetable forms of a 

 very low grade, the germs of fermentation and putrefac- 

 tion, and the probable sources of disease. 



31. It is found that the best filter by which to separate 

 this floating dust from the air is cotton wool, although a 

 handkerchief will imperfectly answer the same purpose. 

 In a lecture on this subject by Prof. Tyndall, he remarks 

 that, " by breathing through a cotton wool respirator, the 

 noxious air of the sick room is restored to practical purity. 

 Thus filtered, attendants may breathe the air unharmed. 



29. The air of rooms in which fever-sick persons are confined ? 



30. Animalcula in the water? Dust in the air ? 



3 1 . The best, air filter ? The remarks of Prof. Tyndall ? 



