146 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



1 J per cent. The presence of such large quantities of volatile 

 oils explained the oleaginous character of the deposits which 

 formed from London smoke, and it had been noticed that, 

 especially in the districts of Manchester where dwelling-houses 

 were much crowded together (e.g., Hulme), the deposit has a 

 similar character." 



The deposits on both out-door and greenhouse foliage have 

 been from time to time collected, as well as the daily accumula- 

 tion on a single pane of glass during foggy weather. The 

 examination of these deposits is not yet concluded. It is 

 interesting to note the presence of a considerable amount of iron 

 oxide in these deposits. This fact may help to elucidate the 

 results of analyses of injured organs. 



The work this winter on this portion of the inquiry can only 

 be regarded as preliminary in its nature. I will state here 

 briefly what lines might be followed in future. Continuous 

 observations from day to day, and sometimes from hour to hour, 

 during dull weather, recording the fluctuating amounts of the 

 hurtful components present in the atmosphere, are much required. 

 These should be obtained simultaneously at a number of selected 

 stations — for the purposes of this investigation situate, preferably 

 near establishments where plants are under cultivation. A know- 

 ledge of the varying amounts of these components would be of 

 the greatest value in making a comparison between the nature 

 of the damage incurred by vegetation in different localities and 

 at different times. 



It is obvious that had we possessed, this winter, stations for 

 fog analysis at, for example, Kew, Chiswick, and South Kensing- 

 ton we should be in a better position to explain the differing 

 effects of the Christmas and February fogs, respectively, at 

 the last named and their very similar action at the first named. 



Dr. G. H. Bailey, of the Owens College, has been devoting 

 himself to a chemical investigation of this character in Man- 

 chester. He has now perfected apparatus by means of which 

 systematic records of the kind indicated can be obtained. The 

 apparatus in question is being fitted up at numerous stations in 

 Manchester, and fully justifies his anticipations as a simple 

 method which does not require manual labour, as is the case with 

 the Meteorological Council's pump. My proposal is that the 

 balance of our grant be used in establishing a number of stations, 



