BACTERIA IN BAKEHOUSE AIR 



87 



idea of the air of underground bakehouses and above-ground bake- 

 houses in Finsbury. Accordingly, the whole of the 30 plates used 

 in this examination were treated exactly the same in every way, the 

 medium, exposure, and temperature and period of incubation being 

 precisely similar. The results, therefore, whilst of little value as a 

 complete examination of the air, are useful and reliable for comparison 

 with each other. 



The results were as follow : 



Inside the bakehouses there was also an interesting distribution 

 of bacteria as follows : 



Illustrations of these two plates are attached (Plate 7). 



From these figures it will be seen (a) that underground bakehouse 

 air contained at least four times more bacteria than street air around 

 it ; (5) at least three times more bacteria than the air of the shop 

 over it ; and (c) at least three times more bacteria than the above- 

 ground bakehouse. The general result of the investigations was that 

 the air of the typical underground bakehouses examined (1) contained 

 14*8 volumes per 10,000 of carbonic acid gas, C0 2 (as compared with 

 4*9 in above-ground bakehouses and 4*3 in the streets of Finsbury) ; 

 (2) that it contained between 10 and 24 per cent, less moisture than 

 outside air surrounding the bakehouses ; and (3) that it contained at 

 least four times more bacteria than surrounding street air, and three 



