CHAPTEE XVI. 



INDUSTRIAL APPLICATIONS OF FERMENTATIVE 

 PROCESSES. 



§1. INTRODUCTION. 



In a work of this nature the minuter details in the fermentation of any 

 particular industry cannot be entered into. ■ It will be sufficient if we 

 indicate the general principles which are followed. In all such 

 industries, what is aimed at is the effecting of a particular change in 

 the substance through the instrumentality of a particular living 

 organism. But as the atmosphere is charged with different kinds 

 of micro-organisms, it is often difficult to keep these out. If they 

 gain entrance, they may set up fermentations which are altogether 

 undesirable and spoil everything. Hence to ensure the predominance 

 of the organism, which sets up the desired fermentation, recourse may 

 be had to two expedients : 



1. To cultivate it under conditions of temperature, moisture, etc., 



which are known to be best suited to its growth. 



2. To give it a start by weakening its competitors. 



If the organism has been isolated, the conditions most favourable to its 

 growth are easily ascertained, and in some of the older fermentative 

 industries the practical experience of centuries has resulted in a very 

 accurate knowledge of the most favourable conditions. The weakening 

 of the competitors is sometimes ensured by the application of heat to 

 the substance to be fermented before the introduction of the desirable 

 organism. In other cases a substance exercising a deleterious effect, 

 which is less injurious to the desired organism than to its competitors, 

 may be introduced. As the organisms are different for each industry, 

 it follows that the conditions insuring the best results will be different. 

 What will remain the same, however, will be the principles governing 



