AIR AND WATER. 69 



Hansen was thus enabled, by a favourable chance, to contrast 

 the state of the air in the most important part of these two 

 breweries ; on the one hand an almost germ-free air, on the 

 other hand an atmosphere teeming with germs. That the 

 product of the latter place must have been affected by the 

 atmospheric conditions then existing admits of no doubt, 

 and this brings us face to face with one of the most important 

 of all facts to the practical brewer i.e., that the air in the 

 fermenting room itself may contain a multitude of those germs 

 which are productive of the most calamitous results. It is, 

 however, possible to keep the air free from these invisible 

 organisms, and there is no doubt that the recorded results 

 are directly due, first, to the purification of the air entering 

 the fermenting-room by passing it over brine, and, secondly, 

 to the rigidly maintained order and cleanliness in the cellars 

 of the Old Carlsberg brewery. Hansen's investigations, 

 therefore, point a moral which cannot be too frequently 

 emphasised. 



Saito carried out very comprehensive investigations on 

 the distribution of moulds at different times of the year in 

 many places in Tokio, both in the open and indoors, with the 

 aid of Soja-gelatine (Soja, decoction of onions and cane sugar), 

 confirming by this means the results of earlier investigations 

 already cited. 



The zymotechnical analysis of water has been of greater 

 value to the brewing industries than the analysis of air. The 

 germs contained in water which give rise to disease in fer- 

 mentations and fermentation products are not usually so 

 enfeebled as those in air, and water on many occasions comes 

 into closer touch with the different products during manufac- 

 ture than does air. The examination of water in reservoirs, 

 and the effect of filtration on the micro-organisms, is of especial 

 practical value. 



A few details may be quoted here from the researches of 

 Holm and of the author as examples of the results obtained 

 from this form of investigation in the fermentation industry. 



Holm's researches showed that among the various micro- 

 organisms in water the moulds are those which develop most 

 quickly in flasks containing wort and beer, and generally also 



