256 PRESENT POSITION OF 



certainty is secured in this respect, and also a rational mode 

 of procedure. This it is which constitutes the advance. There 

 are, however, several other sources of irregularity and danger, 

 and in which the fault cannot be attributed to the pure yeast. 

 As I have previously strongly emphasised, pure yeast cannot 

 do everything. The requirements as to the good quality of 

 the raw products, and a proper and uniform method of 

 working, are the same as before. Another great obstacle to 

 the advance in distilleries and yeast factories is the traffic in 

 secret recipes. In the case of more than one factory, where 

 pure selected yeast has been adopted with success, statements 

 have been made with a view to mislead. 



Before closing this chapter, the following instances of 

 fermentation may be briefly mentioned as bearing some 

 relationship to the above. 



In the preparation of black bread, as carried out in 

 Denmark, so-called leaven (Sauerteig) was hitherto employed. 

 In 1892, however, Schiottz-Christensen, of Copenhagen, pre- 

 pared a pure cultivated yeast, which is now employed in 

 several bakehouses in place of the leaven. 



In 1893, Percival H. Grey showed that only some of the 

 species of Saccharomyces occurring in the yeast employed 

 in the manufacture of Jamaica rum are suitable for this 

 purpose, and that the others are injurious. He therefore 

 recommends the employment of pure cultures of those 

 species which impart to the rum a fine aroma and good 

 flavour. Not only will greater certainty be thereby attained 

 in the manufacture, but, according to his experiments, it will 

 also be possible to some extent to improve the character of 

 the product. 



Went and Prinsen Geerligs obtained similar results in 

 their experiments on the manufacture of arrack in Java. In 

 some distilleries the chief ferment was a mould Monilia 

 javanica, in others Saccharomyces Vordennannii. The arrack 

 obtained by means of the former was inferior to that yielded 



