president's address. 27 



knowledge seems very complete. The agent for decomposition 

 is made in the body of the yeast-plant, in which it remains. Tlie 

 sugar enters the yeast-plant and is split into roughly equal 

 weights of alcohol and carbonic acid gas. To those who have a 

 more extended acquaintance with these objects, it is obvious 

 that much more has to be learnt. We are not aware how the 

 sugar is split into alcohol and carbon dioxide. The arrange- 

 ment of the carbon, hydrogen, and oxygen in glucose does not 

 make it easy to imagine a decomposition into alcohol and carbon 

 dioxide. Further, we have some knowledge that, without other 

 agencies, such as the presence of salts of phosphoric acid, no 

 decomposition of sugar can be accomplished by the ferment. 

 Time will undoubtedly reveal other aspects of this phenomenon 

 at present entirely unsuspected. 



The process of fermentation has not only a scientific aspect. 

 It forms the basis of some manufacturing industries of great 

 antiquity. The preparation of wines, beers, and spirits is an 

 application of this fermentation. Yeast is also used commer- 

 cially in the manufacture of wheaten bread. In making bread, 

 bakers mix Hour, water, and a little salt with a small quantity 

 of a specially prepared yeast at 28*3°C. The dough thus formed 

 is kept warm, when it swells to three times its original volume. 

 At the present time, doughs stand about nine hours in the 

 troughs to ripen. With a greater amonnt of yeast, doughs ripen 

 more quickly, and the time of waiting for the distended dough 

 can be diminished. It is also found that a quantity of one yeast 

 may be much more efficient in liberating gas in the dough than 

 the same weight of another yeast. The yeast obtained by tlie 

 brewers of beer in such large quantities, will not ripen a dough 

 in the time required by a baker, even when used in large quan- 

 tities. A yeast has to possess special characters if it is to bring 

 about alcoholic fermentation rapidly in a baker's dough. At 

 one time it was supposed that some strains or races of yeast 

 were capable of multiplying freely in a baker's dough, while 

 others could not breed quickly under these conditions. It was 

 supposed that it was necessary to search for these yeasts in 

 nature and cultivate them. The capacity of fermenting doughs 



