STUDIES ON FERMENTATION. 343 



flask of a capacity of from 200 to 300 cc. (about 7 to 10 fl. ozs.), 

 in which not more than 100 cc. {oh fl. ozs.) of wort has been 

 fermented, will be sufficient for an apparatus of 1 hectolitre 

 (22 gallons), although the flask may not contain more than 

 1 or 2 decigrammes {Ih to 3 grains) of yeast. In the manu- 

 facture of beer, as at present conducted, the employment of 

 so minute a quantity of yeast would lead to most disastrous 

 results. The fermentation would unfailingly become lactic 

 and butyric, since the foreign germs with which commercial 

 worts and yeasts are always contaminated would have ample 

 time to develop during the first twenty-four or forty-eight hours, 

 whilst the small quantity of yeast used in the pitching could 

 scarcely do more than begin to develop during that time. It 

 is simply with the object of avoiding these secondary fermenta- 

 tions that the brewer uses large quantities of yeast for pitching. 

 After the wort and yeast have been pulled tip* a. process which 

 every practical brewer adopts after pitching, every part of the 

 liquid is occupied by a multitude of yeast-cells, which seize 

 upon the oxygen in solution, germinate with activity, turn to 

 their own account the food-supplies most easily assimilated, 

 and prevent the growth of the germs of disease-ferments. In 

 the new process which we are now explaining, things happen 

 quite difierently. Our wort is pure, and our yeast is pure, and 

 if only a single cell of yeast were introduced into the wort, 

 the vital activity of this would be sufficient to bring about alco- 

 holic fermentation, and to transform the wort into beer, without 

 our having the least reason to apprehend the simultaneous 

 development of any other organisms whatsoever. In short, 

 the new process enables us to pitch with as small a quantity of 

 yeast as we like. It is, nevertheless, inexpedient to employ 

 too minute a quantity, since by doing so we should retard the 

 commencement of fermentation . 



In the case of an apparatus of 5 hectolitres (110 gallons) or 

 double that capacity, the pitching may be accomplished by means 



* [Non-teclmically, stirred about. — Ed.] 



