CHAPTER II. 

 EXAMINATION OF AIR AND WATEK. 



TT^HILST chemical investigations into the composition of 

 air and water reach back into remote times, these 

 researches have only been attempted during the last few 

 decades from a biological point of view. Yet such ample 

 materials have already been accumulated as to justify the 

 assertion that the microbiological composition of both air 

 and water is apt to play an important part, not only in 

 relation to hygiene, but also zymologically. This is obvious 

 from the fact that the various germs which are capable of 

 producing diseases in fermenting liquids, can live in air and 

 in water. 



This part of zymology is, however, still in its infancy, and 

 it may be justifiably asserted that rather too great importance 

 has been ascribed to air, and, still more, to water in their 

 zymological bearings. In the case of normal manufacturing 

 conditions, i.e. where work is carried on with due insight into 

 the principles of rational fermentation, neither of the two 

 factors in question i.e. the microbiological composition of 

 water and air generally affects the operations in a direct 

 manner; but the case is quite different if that insight is 

 wanting, it then becomes possible for those micro-organisms 

 of water and air which are capable of developing under the 

 circumstances, to take root and propagate. But then it is 

 neither water nor air that are essentially to blame. 



The great significance of the biological analysis of air and 

 water lies in the valuable hints which it can give with regard 



