CHAPTER III. 

 EXAMINATION OF AIR. 



The chief points to determine are odour, temperature, 

 pressure, humidity, carbonic acid, ozone, oxidizable and 

 organic matter, noxious emanations, micro-organisms, 

 suspended matter, carbon monoxide, oxygen. 



Examination of a Sample. 



Collection. Large wide-mouthed jars with rubber caps, 

 and holding about 4000 c.c. (4 litres), are most convenient. 

 These are thoroughly cleansed with distilled water before 

 use, run dry by inverting, and capped. Their actual 

 capacity should be ascertained, and marked on them. To 

 collect a sample of air, one of two methods may be 

 employed, namely : 



1. Place jar where sample is to be taken, and blow in 

 the surrounding air by a pair of bellows having a long 

 nozzle reaching down to the bottom of the jar. The 

 contained air is thus displaced from the jar. 



2. Fill the jar with distilled water, and empty it at the 

 place named for sampling by inverting it, and allowing it 

 to drain dry. It is then capped and labelled, and the label 

 inscribed with the observed temperature and pressure and, 

 if not already noted, the capacity of the jar. 



Great care must be exercised not to contaminate any 

 sample with the air breathed out by the observer. 



Odour. The sense of smell exceeds in acuteness any 

 other means used at present to demonstrate the presence 

 of minute particulate matter. It also has a special value 

 in detecting the peculiar fcetid odour so noticeable on first 

 entering an occupied room from the open air. De 

 Chaumont was the first to emphasize this, and he further 

 pointed out the importance of observing it immediately 

 on entering, as the sense of smell is soon blunted. He 

 further pointed out the marked influence of atmospheric 

 humidity in rendering the smell of organic matter more 

 perceptible, an increase of 1 in the humidity being as 



