PURE YEAST CULTURE. 255 



manufacture must therefore be regarded as secured. In the 

 sixth edition of his famous * Handbuch der Spiritusfabrika- 

 tion,' 1894, Maercker mentions the satisfactory results which 

 my reform has effected in this field, and he advocates its 

 general adoption. In his book he gives instructions for the 

 introduction and employment of pure yeast culture in distil- 

 leries, and those who are interested in this subject are referred 

 to the work in question. 



It would carry me far beyond the limits of the present 

 work to attempt to correct the erroneous views which are 

 rooted in these factories concerning the yeast question. 

 Before concluding this chapter I must, however, emphasise 

 one point that is of especial importance in connection with 

 the reaction which has now set in. It is the same error 

 against which I had to contend when I commenced my 

 attempts at reform in the brewing industry. It is, namely, 

 that more is expected of pure selected yeast than from its 

 nature it can accomplish. When we have an ordinary more 

 or less impure yeast which is found to work satisfactorily, 

 the yield will not, as a rule, be increased by the employment 

 of a pure culture prepared from it. To condemn the new 

 system on this account is a mistake. The importance of it is 

 the certainty which it gives. Assuming that the yeast race 

 has been properly selected, it will give the most favourable 

 result, and will continue to do so as long as the conditions of 

 cultivation remain fairly constant. On the other hand, there 

 is no certainty in the employment of the ordinary impure 

 yeast ; its composition may change in a short time to such 

 an extent that it will give anything but a satisfactory 

 result ; in short, with impure yeast we are always dependent 

 upon chance, and we do not in fact know what we are 

 adding to our mash. In the present position of things, the 

 cause of most, and of the worst, irregularities in practice 

 must be looked for in the fermentation. By the introduction 

 of a pure cultivated systematically selected species of yeast, 



