Louis Pasteur : his life and labours / by his son-in-law ; tr. from the French by Lady Claud Hamilton ; with an introduction by John Tyndall.

  • Vallery-Radot, René, 1853-1933.
Date:
1886
Catalogue details

Licence: Public Domain Mark

Credit: Louis Pasteur : his life and labours / by his son-in-law ; tr. from the French by Lady Claud Hamilton ; with an introduction by John Tyndall. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    a light white froth, the wort is transferred to a series of small barrels, which are placed in cellars or store-rooms, kept at a temperature of from 18° to 20° Centigrade. The activity of the fermentation soon causes a foam to rise, which becomes more and more thick and viscous. This is owing to the abundance of yeast which it contains. This yeast, collected in a large trough placed under the casks, is gathered up for future operations. The fermenta- tion lasts for three or four days, then the beer is made and has become clear; the bungs are fixed in the barrels, and they are sent du-ect to the retail dealer or to the consumer. During the transit, a certain quantity of yeast, fallen to the bottom of the casks, thickens the beer, but a few days of repose suffice to make it again clear and fit to drink, or to be bottled. This system of * high' fermentation (so called be- cause it begins at a temperature of 18° to 20°, and is raised one or two degrees higher by the act of fer- mentation itself) is very commonly practised in the north of France, and to a greater extent in the breweries of England. Ale, pale ale, bitter beer, are all beers from high fermentation. The * low ' fermentation, which is almost exclusively employed in Germany, and which is spreading more and more in France, consists in a slow fermentation, at low temperature, during which the yeast settles at the bottom of the tubs and casks. The wort,