EXAMINATION OF AIR AND WATER. 47 



organisms which occurred in the air of these cellars were : 

 Saccharomyces cerevisiae, Mycoderma cerevisise, Sacch. Pastori- 

 anus, Sacch. ellipsoideus, Torula Pasteur, and other yeast-like 

 forms ; further, Penicillium, Dematium, Cladosporium, and rod 

 bacteria. HANSEN was thus enabled, by a favourable chance, 

 to sharply 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 influenced 

 by the atmospheric conditions then existing admits of no doubt ; 

 it serves to impress us with 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 multitude of 

 those germs ivhich 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 fermenting-room by passing 

 it over brine, and, on the other hand, the very rigidly main- 

 tained order and cleanliness in the cellars of the Old Carlsberg 

 brewery stand in direct relation to the above-mentioned result. 

 HANSEN'S investigations, therefore, point a moral which cannot 

 be too frequently emphasised. 



Zymotechnical examinations of water according to the 

 principles laid down by HANSEN (a description of which is 

 given in the sequel) were carried out on a large scale by 

 J. CHR. HOLM (Carlsberg Laboratory), and also in the author's 

 laboratory. 



HOLM'S researches show that among the various micro- 

 organisms the moulds are those which develop most quickly in 

 flasks containing wort and beer, and generally also those which 

 occur in largest numbers in the flasks. Penicillium glaucum 

 and Mucor stolonifer were found among them. 



Next to the moulds come the bacteria, if wort is infected 

 with the water, whilst if sterilised beer is used, they developed 

 only scantily. The following bacterial forms were found : 

 Bacterium aceti, Bact. Pasteurianum, a third form which made 

 the beer slimy and ropy ; and lastly, species were frequently 

 found which imparted a disgusting smell to the wort. 



Of rarest occurrence in the experiments here referred to 



