EXAMINATION OF AIR AND WATER. 47 



The greatest interest, however, attaches to the examina- 

 tion of the different fermenting-rooms, partly in u Old 

 Carlsberg " and partly in the brewery " N." In the first- 

 mentioned rooms the air contained fewer organisms than in 

 any of the localities examined in the whole research ; in the 

 fermen ting-cellars of the brewery " N," on the contrary, a 

 large number of the flasks (55-75 to 100 per cent.) became 

 infected. The organisms which occurred in the air of these 

 cellars were : Saccharomyces cerevisise, Mycoderma cerevisise, 

 Sacch. Pastorianus, Sacch. ellipsoid eus, Torula Pasteur, and 

 other yeast-like forms ; further, Penicillium, Dematium, 

 Cladosporium, and rod bacteria. Hansen was thus enabled 

 by a favourable chance, to show the following contrast in the 

 state of the air in the most important place in the two 

 above-named 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 at this time 

 must have borne the stamp of this condition admits of no 

 doubt, and we find here one of the most important of all 

 facts connected with the practice of the fermentation 

 industries. The air in the fermenting room itself may 

 contain a world of those germs which are productive of the 

 most calamitous results ; it is, however, possible to keep the 

 air free from these invisible germs, and it admits of no doubt 

 that, on the one hand, the purification of the air entering 

 the fermen ting-room by passing it through a salt-water bath, 

 and, on the other hand, the very rigidly maintained order and 

 cleanliness in the cellars of the Old Carlsberg brewery stand 

 in direct relation to the above-mentioned result. Hansen's 

 investigations, therefore, here again contain a warning which 

 cannot be repeated too frequently. 



Based upon a long series of comparative investigations, 

 Hansen gave the following method for the zymotechnical 

 analysis of air and water. 



The principle of this method of air- and water-analysis is 

 as follows: For brewing purposes it is only necessary to 



