34 



1. Common country road dust, due to the attrition of solid matter— 

 the hoofs of the horse and the wheels of the vehicle on the road material, 

 the stone or gravel or merely the common dirt. This kind of dust is 

 mixed with only a small amount of other, vegetable, matter, the drop- 

 pings of horses chiefly. From a sanitary standpoint it is not very ob- 

 jectionable, although it may be so esthetically. 



2. City dust, the dust of the sanitarian, the dust par excellence. City 

 dust has "a complex composition. Most of it comes from the droppings of 

 horses and originally existed in the form of hay, oats and corn. The fine- 

 ness of the particles depends on the length of time it remains on the street 

 to be pulverized by trafiic. The wear of the street paving material under 

 the horse's hoof and of vehicles adds an appreciable amount; more is 

 added by litter falling from passing wagons, or is brought in from the 

 mud roads adhering to the wheels. Soot, due to the imperfect com- 

 bustion of coal, lends character to the citj' dust and in our American 

 cities there is much of it. especially during the cold season of the year. 

 Man himself adds not a little directly: the wear and tear of clothing and 

 the shedding of epidermal scales adds a minute quantity— and much 

 comes from his moutli. in the form of tobacco juice, saliva, and the 

 abnormal secretions due to an unhealthy condition of the mucous mem- 

 branes. City dust acquires peculiar propos'ties on this account and thus 

 making it differ radically from all other forms of dust. 



More might be said on the causation of dust, but much more can be 

 said concerning its influence or effects, and to this I will now turn. 



Effects of Dust: The most noticeable effect of city dust is that it 

 makes a city, its houses and inhabitants, look dirty. The dust is Ijlown 

 all about and settles over everything, indoors and out, and the house- 

 wife is kept busy trying to keep things looking clean. 



There is an old saying about an ill wind that blows nobody good. 

 The laundryman flourishes in a dusty city, clean linen means frequent 

 laundering. The doctor flojrishes because dust means sickness and 

 disease. "There is good money in that for me," a phj-sician remarked, as 

 a dense cloud of dust was seen coming down the street. But the indi- 

 vidual, par excellence, benefited is the patent medicine man; he flourishes 

 exceedingly in a dusty city and his nostrums are in great demand. 



Now this brings up a phase of city life and of the city dust ques- 

 tion tliat is rarely considered. The scientist who has no medical educa- 

 tion and no iiracticni experience witli iiilnients and diseases can not 



