DUST. 3 



proved by delicate experiments that when all dust was 

 removed from the track of a beam of light, there was 

 darkness. So before the command, "Let there be 

 light," the dust condition of light must have been pres- 

 ent. Balloonists find that as they ascend higher the 

 color of the sky deepens. At a distance of some miles 

 the sky is nearly black, there is so little dust to scatter 

 the rays of light. If the stellar spaces are dustless, 

 they must be black, and therefore colorless. The mois- 

 ture of the air collects about the dust-particles, giving 

 us clouds, and with them all the glories of sunrise 

 and sunset. Fogs, too, are considered to be masses 

 of "water-dust," and ships far out at sea have had 

 their sails colored by this dust while sailing through 

 banks of fog. 



Astronomers find meteoric dust in the atmosphere. Meteoric 

 When this falls on the snow and ice fields of the Arctic 

 regions it is readily recognized. The eruption of Kra- 

 katoa proved that volcanic dust is disseminated world- 

 wide. 



An old writer has said : "The sun discovers atomes 

 though they be invisible by candle light, and makes 

 them dance naked in his beams." 



Thus dust, just common every-day dust, is a very source 

 important and complex substance, which promises 

 much of interest in its study. Therefore, again we ask 

 where does it come from and of what is it made? 



When a March wind blows over a sandy road or a 

 November gale sweeps through city streets, it is evi- 

 dent that a large part of the dust found in the house 



