238 THE POPULAR SCIENCE MONTHLY. 



DUST AND FRESH AIR. 



By T. PEIDGIN TEALE, E. K. S. 



EXCEPT in the case of museums, few serious attempts have 

 been made to exclude dust from rooms, closets, cupboards, 

 and drawers, to the contents of which, not infrequently, dust is 

 simply ruinous. We allow dust to run riot among our things of 

 value, and then go to considerable expense to render them clean 

 again, only to start them on a fresh career of defilement. 



Looked at in the abstract, is not our passive capitulation to 

 dust incomprehensible ? When I enter an office in a town and 

 see the window-sills and papers dotted with soot, or go into a bed- 

 room and see the toilet-table defaced with blacks, and know that 

 the soot and the blacks need not be there, I can not refrain from 

 asking how comes it to pass that we so patiently submit to such 

 perpetual discomforts. You will doubtless reply, We agree with 

 you as to the existence of the evil, but how is it to be remedied ? 

 My object is to offer some practical suggestions whereby you may 

 so far mitigate and reduce the evils of soot and dust as to make 

 them tolerable, perhaps even to lay down principles by which the 

 evils can be annihilated in those instances in which the result to 

 be obtained is worth the cost of achievement. For the practical 

 purposes of every-day life it may turn out that we had better 

 be content with approximate perfection, a condition of existence 

 which compels us to be content with approximately pure water 

 from a filter, and approximately pure air in our living-rooms. 



If dust is to be kept out of any cavity, we must first find out 

 why the dust gets in, in spite of good workmanship and accurate 

 fitting. The reason is simple, ridiculously simple when stated, 

 but, curiously, it has been little, if at all, thought of, and certain- 

 ly hardly ever acted upon in practice. And the reason is this : 

 Closets, cupboards, drawers, and boxes contain air ; if the air were 

 inelastic and never altered in volume, there would practically be 

 no entrance of dust into these closed cavities. Unfortunately for 

 our cleanliness, air is changing in volume incessantly. We are 

 all familiar with the barometer, and most of us no doubt under- 

 stand why the quicksilver rises and falls in the glass tube, or why, 

 in the aneroid barometer, the index moves to right or left. Let 

 us consider what these changes mean, and what they record. 



When the air around us becomes condensed shrinks into a 

 smaller volume it becomes heavier, puts greater pressure on the 

 surface of the mercury, and makes it ascend in the tube ; then the 

 mercury is said to rise. When the air expands swells into a 

 larger volume it becomes lighter, the pressure on the mercury 



