CHAPTER II. 

 Examination of Air and Water. 



As the water was hitherto regarded as one of the obscure 

 factors in the fermentation industries, and had often to 

 bear the blame of irregularities which could not be explained 

 in any other way, so also many peculiarities in the results 

 obtained at a certain point have at all times been considered 

 to originate from the air. In this was involved a vague 

 misgiving that this invisible air contained substances which 

 act prejudicially to our operations the nature of these 

 substances, and how it was possible to obtain a closer know- 

 ledge of them, was, until the most recent times, involved in 

 obscurity. Chemical investigations of the air, which have 

 been carried out for more than a century, gave no information 

 on this point. 



In the course of time a new factor was added ; it was 

 incontestably proved that the air is not everywhere equally 

 favourable to the human system ; there might possibly be 

 something present which attacked our organism; this 

 unknown matter was called "Miasma" (mixture), the word 

 being taken in a purely chemical sense. Since, however, 

 these miasmata were not traced further, science was thereby 

 not advanced one step. 



The discoveries of Spallanzani (mentioned in the last 

 chapter), and of later investigators, opened up an entirely 

 new path, namely, the study of micro-organisms. Pasteur 

 especially showed that these micro-organisms are of essential 

 importance to the fermentation industries, when he proved 

 that the air contained both bacteria and alcoholic ferments. 



