43& Phenomena connected with Cloudy Condensation. [Apr. 28, 



rooms by open flames. The room in which the tests were made is 

 24 X 17 x 13 feet. The object of the tests was to see if the koni- 

 scope could tell us anything definite about the degree of pollution at 

 the different parts of the room, and also about the rate at which it 

 was increasing. For this purpose a small tube was arranged so that 

 one end of it could be raised to the ceiling, or into the air of any part 

 of the room from which it was desired to take the air ; the other end 

 of the tube was connected with the koniscope. 



The first thing to be done was to examine the air of the room 

 before lighting the gas and beginning the tests. On doing this the 

 air at the level of the observer gave a very faint colour, scarcely per- 

 ceptible ; air drawn from within 3 inches of the ceiling gave equally 

 little colour, and the air inside the room gave the same colour as the 

 air outside. The upper end of the tube connected with the koniscope 

 was then raised to within 3 inches of the ceiling, near one end of the 

 room, and the koniscope left attached to the lower end ; three jets of 

 gas were now lit in the centre of the room, and observations at once 

 begun with the koniscope. Within thirty-five seconds of striking the 

 match to light the gas the products of combustion had extended to the 

 end of the room ; this was indicated by the colour in the koniscope 

 suddenly becoming of a deep blue. In four minutes the deep blue- 

 producing air was got at a distance of 2 feet from the ceiling. In ten 

 minutes there was strong evidence of the pollution all through the 

 room. It was strongly indicated near the windows, owing to the down 

 current of cold air on the glass. This impure down current could be 

 traced to the floor, and onwards to the fireplace ; while a pure current 

 could be traced from the door to the fireplace. In thirty minutes the 

 impurity at 9 feet from the floor was very great, the colour being a 

 deep blue. 



The wide range of the indications of the koniscope, from pure 

 white to nearly black- blue, makes the estimates of the impurity very 

 easily taken with it ; and, as there are few parts to get out of order, 

 it is hoped it may come into general use for sanitary work. 



The few experiments I have made with this instrument have 

 clearly pointed out that a window is not an unalloyed blessing as 

 regards the purity of the air in our rooms, however much we may 

 have been in the habit of thinking otherwise. In all cases it has been 

 found that in rooms where gas is burning the air near the window is 

 very impure. This imp are down current of air near the window has 

 been traced by the koniscope in all rooms tested. The impurity is 

 caused by the cold air on the window sinking, and drawing down the 

 impure air near the ceiling, and this impure air is mixed with the lower 

 air which we are breathing. This effect is, of course, greatest when 

 the windows are unprotected by blinds, shutters, or curtains. It is 

 evident that though a window may supply pure air when it is open, 



