388 TRANSACTIONS OF SECTION B. 



together, it is probable that the steady application of pressure by public 

 authorities will in time have its effect in a large reduction of f actoiy smoke. 



The most hopeful field for laboratory research lies in the reduction of 

 domestic smoke by improvements in coal and coke fires, gas-fires, and by 

 developing the use of semi-coked coal. 



The Manchester Air Pollution Board, with an annual grant of about 4501. 

 available for its work, has undertaken two lines of research. In the fii'st place, 

 it was decided to co-operate in the national investigation by measuring the 

 deposition of soot, and also the cutting off of sunlight at ten different stations 

 in or near Manchester; and, secondly, a room has been fitted up at the School 

 of Technology for the purpose of carrying ovit tests on various kinds of domestic 

 heating appliances, with a view to giving independent and authoritative advice 

 to" consumers on the best types of such appliances. It is hoped that similar 

 Research Committees will be appointed by other municipalities, and that the 

 British Association will appoint a Committee to co-ordinate the work of such 

 local Committees. 



Professor W. W. Haldane Gee (of the Manchester School of Technology) 

 reviewed the efforts made in Manchester since 1842 to mitigate the smoke 

 nuisance, and described some of the instruments and experimental methods used 

 in the recent work of the Air Pollution Advisory Board {vide Report, loc. cit.), 

 and the development of the electrical means of causing deposition of dust and 

 soot.^ 



Professor E. Knecht (of the Manchester School of Technology) described 

 the results of investigations on the composition of Manchester soot and the 

 various products obtainable therefrom. 



(ii.) The Work of the Sheffield Health Committee. 



Professor Wynne (Sheffield University) called attention to the results 

 obtained from an investigation of rain-water collected in standard soot-gauges 

 exposed at four sites in the Sheffield City area during the period July 1, 1914, 

 to June 30, 1915. The investigation, which had been promoted by the Health 

 Committee of the City of Sheffield, and carried out in conjunction with the 

 University, showed that if an opinion as to the contribution of house-fires to 

 pollution of the atmosphere may be based on the proportions of tar and of 

 ammonia collected by the rain (these arising from imperfect combustion of fuel 

 in fire-grates), no material difference could be traced between the values for the 

 summer and the winter six months. The data obtained for the Attercliffe site, 

 in the east end of the city, where the armament works are situated, gave values 

 which were roughly about twice as great as those for the other sites, respectiveh' 

 N.N.W., W., and S. of the centre of the city, and attention was directed to the 

 remarkable approach to uniformity in the results obtained from these three 

 sites, which seemed to be independent of the direction of the prevailing wind 

 as recorded each month. 



Professor Wynne urged the necessity of creating public opinion on the subject 

 of atmospheric pollution, and supported warmly the suggestion that the British 

 Association should take iip the question through a Committee on which various 

 interests were represented, as had been done by the Sanitary Committee of the 

 City of Manchester. 



(iii.) Damage to Vegetation caused by Atmospheric Pollution by Smoke. 



Mr. A. G. RtrSTON (Leeds University), in describing the results of investiga- 

 tions recently carried out in and near the City of Leeds, pointed out that the 

 damage caused by coal-smoke to vegetation is due partly to the smoke-cloud 

 reducing the amoiuit of available sunlight, at times by as much as 54 per 

 cent. The black deposit upon the leaves still further hinders the sunlight from 

 getting into contact with the green colouring-matter of the leaf, while the acids 

 present in the smoke damage the structure of the leaf and hasten its fall. 

 Damage is also done to the roots of plants growing in smoke-infected areas, 

 possessing few root-hairs or fibrous roots. Moreover, the acid rain falling on the 

 soil limits the activity of the bacteria in the soil, for unfortunately the most 

 useful nitrifying organisms are the most susceptible to acid influences. It has 



' Proc. Amer. Instit. of Electrical Engineers, April 1915. 



