242 



STUDIES ON FERMENTATION. 



fermentation, and when this small quantity of liquid was in full 

 fermentation, and the yeast in it was young and vigorous, we 

 opened the tap, closing it again immediately, so that a little of 

 the liquid and yeast still remained in the funnel. By this 

 means wc caused the liquid in A to ferment. We also impreg- 

 nated the liquid in B with some yeast taken from the funnel of 

 A. We then replaced the porcelain dish in which the curved 

 escape tube of A had been plunged, by a vessel filled with 

 mercury. 



The following is a descrij)tion of two of these comparative 

 fermentations and the results they gave. 



The fermentable liquid was composed of yeast- water sweetened 

 with 5 per cent, of sugar-candy ; the ferment employed was 

 saccharomyces pastorianus. 



The impregnation took place on January 20th. The flasks 

 were placed in an oven at 25° C. (77° F.). 



Flask B, with air. 



January 21st. — A sensi- 

 ble development of yeast. 



The following days, 

 fermentation was active, 

 and there was an abun- 

 dant froth on the surface 

 of the liquid. 



February 1st. — All 

 symptoms of fermenta- 

 tion had ceased. 



Flash A, without air. 



January 21st. — Fermentation commenced ; 

 a little frothy liquid issued from the escape- 

 tube and covered the mercury. 



The following days, fermentation was 

 active. Examining the yeast mixed with the 

 froth that was expelled into the mercury 

 by the evolution of carbonic acid gas, we 

 found that it was very fine, young, and 

 actively budding. 



February 3rd. — Fermentation still con- 

 tinued, showing itself by a number of little 

 bubbles rising from the bottom of the liquid, 

 which had settled bright. The yeast was at 

 the bottom in the form of a deposit. 



February 7th. — Fermentation still con- 

 tinued, but very languidly. 



February 9th.— A very languid fermen- 

 tation still went on, discernible in little 

 bubbles rising from the bottom of the flask. 



As the fermentation in A would have continued for a long 

 time, being so very languid, and as that in B had been finished 

 for several days, we brought to a close our two experiments on 



