166 ANSWERS TO PRACTICAL QUESTIONS 



intrusive particles that, swept inward by the breath, would 

 otherwise pass into the lungs. 



33. Can one really if draw the air into his lungs " ? 



(See Physiology, p. 80.) 



Strictly speaking, no. In the act of inspiration we so con- 

 tract the muscles as to enlarge the cavity of the chest, thus re- 

 ducing the pressure upon the lungs, upon which the external 

 atmosphere, in seeking an equilibrium, rushes in to fill the 

 space. 



34. How often do we breathe ? 



Ordinarily about eighteen times a minute. 



35. Describe some approved method of ventilation. 



(See Physiology, p. 92.) 



36. What is at once the floor of the chest and the roof 

 of the abdom,en ? 



The diaphragm. 



37. What would you do in case of apparent death by 

 drowning or by coal-gas ? 



(See Physiology, p. 264.) 



38. What would you do in case of croup, 'while the 

 doctor was coming ? 



(See Physiology, p. 260.) 



39. How would you treat a severe burn ? 



(See Physiology, p. 257.) 



40. Describe the various ways in which the water in a 

 well is liable to become unwholesome. 



In towns and cities organic matter, solid or in solution, 

 permeates the soil to the depth of several feet, and shallow 

 wells are therefore quite certain to be polluted, as any earth 

 used constantly as a filter will, in the course of years, lose its 

 purifying properties. Wells, too, are often placed in dangerous 

 proximity to cemeteries, cess-pools, barn-yards, vaults, etc., and 

 in many cases receive direct drainage from these pestilential 

 sources. Impurities will collect in wells that are not periodic- 



