14 Dr. G. H. Bailey on 



The maximum so far recorded for town air is 38*1, and 

 the minimum O'l — a sufficiently wide difference to serve as a 

 means of indicating, in a very marked manner, the extent 

 of pollution of air under varying atmospheric conditions, 

 while within the same city there are also sufficiently wide 

 differences. Common experience of the condition of the 

 air in the respective localities, and under the conditions 

 given, will lend support to such a differentiation as is shown 

 in the numbers given. 



Without going further into results which, however, can 

 be seen by referring to the work of the Air Analysis Com- 

 mittee, I may say that a contrast quite as striking is found 

 in regard to the amount of suspended organic matter in the 

 air, and the quantity which is deposited from the air within 

 these areas. Moreover, if we further examine the nature 

 of the organic matter so occurring, it is found to be more 

 noxious in the districts which, on all the evidence, appear 

 to show the highest amount of pollution. Indeed, a careful 

 enquiry into the nature of the organic matter in the air of 

 thickly-populated districts and in dwellings would, I am 

 sure, be of extreme value, and is worthy of the attention of 

 those interested in the sanitary condition of our towns. 

 Though it is not the province of this paper to deal with the 

 air of dwellings, there is one point which is so much to the 

 point in speaking of pollution by sulphur compounds, that 

 I cannot omit it, more especially as it bears directly on the 

 succeeding part of this paper, namely, the sulphur com- 

 pounds which accumulate in the air of rooms lighted by 

 Manchester coal gas. In March and April of last year, 

 some analyses were made of the air of Professor Dixon's 

 room at the Owens College. The dimensions of the room 

 are 20 feet square and 13 feet high. Three burners, 

 consuming about twelve cubic feet of gas per hour, were 

 lighted at five in the evening, and then air was aspirated 

 from different heights in the room between the hours of 



