26 HUMAN BIOLOGY 



long series of experiments to be enormous, for with the or- 

 dinary methods of " cleaning " these rooms, very few of 

 the germs are removed. When a room is swept, most of 

 the light dust particles are raised from the floor and mingled 

 with the air. After a short time the room is " dusted," 

 often with a feather duster. The bacteria which may have 

 settled are whisked off again into the air. Experiments 

 have shown, too, that the number of germs in a room is 

 not materially diminished by ventilating currents, unless 

 there is a strong draught. 



Most of this germ dust can, however, be removed from 

 our homes if they are cleaned in a proper manner. In a room 

 that has not been used for three or four hours practically all 

 of the bacteria and fine dust particles have settled out of 

 the air upon the horizontal surfaces. For dusting, a cloth 

 should always be used. " Dustless dusters " may be bought 

 or prepared by soaking a piece of cheesecloth or flannel in 

 a mixture of wax and turpentine, or by slightly sprinkling 

 cheesecloth with water. By the use of these cloths most of 

 the particles of dirt may be taken up and then removed from 

 the cloths by washing. If carpets, rugs, and draperies are 

 then cleaned with a vacuum cleaner, practically no dust is 

 raised (Fig. 11) ; hence, further dusting is unnecessary. 

 Careful investigation has demonstrated that the use of a 

 vacuum cleaner on surfaces that may be washed or wiped 

 with a cloth is too expensive a method of cleaning, and that 

 it is not nearly as effective. 



It is much more hygienic to have floors covered with rugs, 

 for if a vacuum cleaner is not available, the dusty rugs 

 and draperies may be removed from the room and cleaned in 

 the open air. In general, a carpet sweeper is to be preferred 

 to a broom as a means of cleaning carpets, since, as Fig. 1 1 

 shows, fewer germs are stirred up when the former is used. 



