Page:The character and extent of air pollution in Leeds - (A lecture delivered before the Leeds Philosophical Society, on March 3rd, 1896.) By Julius B. Cohen (IA b21534160).pdf/9

9 coal. From house coal I have found, from a number of analyses, that the average is over five per cent. The domestic hearth is therefore an important factor in the smoke nuisance. How far we can hope to solve successfully the problem of preventing house smoke by the use of gas or coke, it is difficult to say. Mr. Russell and I have carefully studied the question of gas fires from this point of view, and our results are embodied in a small pamphlet, which members of this Society may obtain gratuitously from Mr. Jackson, bookseller, of Leeds. I am afraid that the present high price of gas will offer the main obstacle to its general use.

Supposing, then, that of the 4,000 tons of coal burnt daily in Leeds, one-half per cent. only escapes into the air as soot, this will represent 20 tons of soot a day.

Now I must ask you to follow me through a simple calculation. The thickly populated part of Leeds covers about four square miles, with the Parish Church as centre. We will call these four square miles the smoke infected area. That does not imply that the smoke does not extend beyond, but it is most concentrated in that region. If there are 20 tons of soot delivered to the air in 12 hours, and if the air is renewed on the average 50 times in 12 hours, as there is reason to believe, then there is in the infected area, at any one moment, 8 cwt. of soot in suspension. Now, Angus Smith estimates that the smoke probably rises to a height of 300 feet on the average, before being dispersed. We can calculate on this assumption how much soot there is in 100 cubic feet. It works out to almost exactly 1&middot;2 milligrammes. If then there are 20 tons of soot sent into the air in the day, and the other factors