DUST AND DAMPNESS. 115 



from the street even at the risk of the lives of those men who 

 had to work under the carts and horses feet in the crowded streets 

 to do it. 



President Walcott said that London and Paris are two great 

 cities, — the former outwardly ding}', while the latter, so far as 

 outward appearance goes, represents absolute cleanliness. Lon- 

 don was formerly' dirt}', but for the last thirty years a marvellous 

 change has been going on until it has become the cleanest large 

 city in the world, and the death rate is lower than in Paris. 



The lesson to be learned from what has been said today is that 

 it is utterly impossible to get entirely rid of dust, and, paradoxical 

 as it seems, perhaps we could not exist if we did. If we disinfect 

 the air of this room we destroy the life of every human being in 

 it. We must strike the balance of inconveniences, and take the 

 least. The conclusion of the whole matter is, keep clean. 



William C. Strong suggested that sulphurous acid gas, which 

 destroys mildews and other fungoid growths, might destroy the 

 lower forms of animal life which have been mentioned in this 

 discussion. 



President Walcott said that in dealing with mildew and similar 

 fungi we have plants very easy to destroy ; but bacteria are very 

 difficult to destroy, and when we come to the spores it is almost 

 impossible to destroy them ; some of them have survived a tem- 

 perature above that of boiling water. 



Mrs. Richards remarked that if the walls of a room could be 

 washed down with a solution of sulphurous acid it would be 

 better than merely to have the air impregnated with sulphurous 

 gas. 



President Walcott cited one laboratory experience as showing 

 how difficult it is to destroy the bacteria and other organisms 

 which are found in dust. In this laboratory an investigation was 

 made of the bacillus of anthrax. During the time occupied in 

 that work the laboratory became stocked with the spores of that 

 bacillus, and as all efforts to eradicate them proved futile, the 

 whole establishment was rendered useless for further scientific 

 research in this direction. 



Mrs. Richards stated that, with other substances, dust some- 

 times contains the pollen of plants. Its composition is influenced 

 by local causes. The "red snow," of the Arctic regions, takes 

 its color from the spores of algae, which are carried over it by the 



