A patriot to the heart's core, he learned with poignant grief the news of his country's disasters. The bulletins of defeat, which succeeded each other with mournful monotony, threw him into deep despair. For the first time in his life he had not the strength to work. He lived at his little house in Arbois as one completely vanquished. Those who went into his room found him often bathed in tears. On January 18, 1871, he wrote, to the Dean of the Academy of Medicine at the University of Bonn, a letter in which all his grief and all his pride as a Frenchman were displayed, requesting him to withdraw the diploma of German doctor which the Faculty of Medicine of the University had conferred upon him in 1868. Whilst he wrote this letter, which was a cry of patriotism, his son, enrolled as a volunteer, though hardly eighteen years of age, was gallantly doing his duty in the Army of the East.
STUDIES ON BEER.
The war was over. Little by little the life of the country was resumed, and with returning hope the desire and necessity for renewed work. After two years of infirmity, Pasteur at length began to feel the recovery of health. It was like a slow and gentle renewal of all things. He wished to return as soon as possible to his laboratory in Paris to put into execution projects of experiments which had long been working in his brain. At the moment when he was preparing to start, the rebellion of the Commune broke out. M. Duclaux, who had become Professor of the Faculty of Sciences in Clermont-Ferrand, offered the use of his laboratory to his old master. Pasteur accepted it. Eager to commence an investigation which would bring him again to the study of fermentation, he attacked the diseases of beer. But it was not only for the purpose of creating a new link between these researches and his former ones that he occupied himself with this subject, he was also influenced by a somewhat patriotic idea. He dreamt of success in an industry in which Germany is superior to France. He hoped by means of scientific principles, by which commerce would largely profit, to succeed in making for French beer a reputation equal, if not superior, to that of Germany.
Beer is much more liable to contract diseases than wine. It may be said that while old wine is often to be found, there is no such thing as old beer. It is consumed as fast as it is made. Less acid and less alcoholic than wine, beer is more laden with gummy and saccharine matters, which expose it to rapid changes. Thus the trade in this beverage is constantly struggling with the difficulties of its preservation.
The manufacture of beer is simple. It is extracted from germinated barley, or malt, an infusion of which is made and gradually heated to the boiling point. It is then flavoured by hops. When the infusion of malt and hops, which is called 'wort,' is completed, it is subjected to a cooling process, and drawn off into tuns and barrels. It is then that alcoholic fermentation sets in. The cooling ought to be performed rapidly. While the wort is at a high temperature there is nothing to fear, it remains sound; but under 70° Centigrade, and particularly between 25° and 35°, it is easily attacked by injurious ferments—acetic, lactic, or butyric. After the wort is cooled, a little of the yeast proceeding from a former fermentation is added to it, in order that the whole mass of the wort should be invaded as soon as possible after its cooling by the alcoholic ferment alone—the only one, properly speaking, which can produce beer. If this wort were treated in the same way as the must of the grape, if it were abandoned to fermentation without yeast—to so-called spontaneous fermentation—this would hardly ever be purely alcoholic, as in the must of grapes, which is protected by its acidity. Most frequently, instead of beer, an acid or putrid liquid would be obtained. Divers fermentations would simultaneously take place in it. When the wort has fermented and the beer is made, there is still the fear of its rapid deterioration, which necessitates its being quickly consumed. This condition is sometimes disastrous to those employed in the beer trade; and the improvements in the manufacture of beer which have been made during the last forty years have all had for their object the removal of this necessity for the daily production, so to speak, of an article of which the consumption is liable to constant variations.
Formerly only one kind of beer was known, the beer of high fermentation. The wort, after having undergone cooling in the troughs, is collected in a large open vat at a temperature of 20°, and yeast is added to it. When the fermentation begins to show itself on the surface of the liquid, by the formation of 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 fermentation 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 direct 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 because it begins at a temperature of 18° to 20°, and is raised one or two degrees higher by the act of fermentation 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.