102 HOUSEHOLD BACTERIOLOGY 



tion when dusting should be done, if the aim of dust- 

 ing be to remove dust from the house. If, then, these 

 and other experiments have shown that at least two 

 hours are required to free the air of a still room from 

 the bacteria present in its dust, it is of little use to 

 dust immediately after sweeping. When this is done, 

 no wonder the housewife exclaims in despair, "Why, 

 this room was dusted this morning, but you never 

 would have known it !" 



While we cannot always let two hours elapse be- 

 tween some dust-spreading process of housework, like 

 sweeping or bedmaking, we can remember that the 

 raised dust must settle before we can remove it. Wait 

 as long as possible ! 



When Fig. 46 is compared with Fig. 47, the reason 

 is plainly seen why rugs mean less dust than carpets 

 and therefore a cleaner, healthier house, because these 

 can be carefully rolled, cleaned out of doors, and the 

 floor wiped with a damp cloth. 



Bed-making Next to sweeping as a dust-raising and dust-spread- 

 ing process comes bed-making. 



Fig. 48 shows a plate planted just after a bed had 

 been made. The colonies of bacteria and molds in this 

 plate had been growing for a longer time when the 

 photograph was taken than in plates Fig. 46 and Fig. 

 47. Two of the molds on this plate are very mature, 

 being black with spores. 



As health requires that the air of the sleeping room 

 be as free from dust as possible, considerable time 



