i8 Ciiiciiniati Society of Natural History. 



his pocket, by which he can count the number of particles in 

 the air at any place. He has counted 7.500,000 of dust 

 particles in one cubic inch of the ordinary air of Glasgow ; 

 4,000,000 in a cubic inch of air outside the Royal Society 

 Rooms, Edinburg ; inside the rooms, after the fellows had met 

 for two hours, on a winter evening, the fire and gas having 

 been burning, 6,500,000 in a cubic inch, four feet above the 

 floor, but near the ceiling no fewer than 57,500,000 in the 

 cubic inch ; in one cubic inch of air right above a Bunsen 

 burner 489,000,000 of dust particles. These fog deposits have 

 also been weighed, so that in the Chelsea district of London 

 it amounted to the rate of six tons to the square mile. Purely 

 gaseous emanations can not pass away from a town while fog 

 exists. Take four in 10,000 volumes of air as the normal 

 proportion of carbonic acid, in case of a dense fog, it 

 amounted to as much as 14.1, thus seriously contaminating 

 the air while it lasts. The analysis of fog deposits at Chel.sea 

 showed : 



Carbon 39.0 



Hydrocarbon 12.3 



Organic bases (pyridines) 2.0 



Sulphuric acid 4.jy 



Hydrochloric acid 1.4 



Ammonia 1.4 



Metallic iron and magnetic ore iron 2.6 



Mineral matter (chiefly) silica and ferric oxide . . . 31.2 

 Water, not determined (say difference) 5.S. 



1 00.0 



It is said of this deposit, " it was like a brown paint, it 

 would not wash off with water, and could only be scraped off 

 with a knife." The fog collected from Ancuba leaves at Man- 

 chester had six to nine per cent of sulphuric acid and five to 

 seven per cent of hydrochloric acid. Three days of fog in 

 Manchester deposited per square mile of surface one and a 

 half per cent sulphuric acid. 



Dr. Russel shows, from the Registrar Generars report, that 

 the fogs are followed by an increa.sed death rale, mainly by 

 rea.son of the fact that fogs are accompanied with falls of 

 temperature. In one case, where there was a temperature 

 above the average, the death rate was not increa.sed. There is 



