Fermentation and its bearings on the phenomena of disease : a discourse delivered in the City Hall, Glasgow, October 19th 1876 : under the auspices of the Glasgow Science Lectures Association / by John Tyndall.
- John Tyndall
- Date:
- 1877
Licence: Public Domain Mark
Credit: Fermentation and its bearings on the phenomena of disease : a discourse delivered in the City Hall, Glasgow, October 19th 1876 : under the auspices of the Glasgow Science Lectures Association / by John Tyndall. Source: Wellcome Collection.
Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.
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![r to the grape. At the vintage the fruit of tlie vine is placed in prosier vessels, and abandoned to its OAvn action. It fer- ments, producing carbonic acid; its sweetness disappears, and at the end of a certain time the tinintoxicating grape- juice is converted into intoxicating Avine. Here, as in the case of the cherries, the fermentation is spontaneous—in what sense spontaneous will appear more clearly by-and-by. It is needless for me to tell a Glasgow audience that the beer-brewer does not set to work in this Avay. In the first ]3lace the brewer deals not with the juice of fruits, but with the juice of barley. The barley having been steeped for a suflficient time in water, it is drained, and subjected to a temperature sufficient to cause the moist grain to germinate, after which it is completely dried upon a kiln. It then receives the name of malt. The malt is crisp to the teeth, and decidedly sweeter to the taste than the original barley. It is groiuid, mashed iip in warm water, then boiled Avith hops until all the soluble portions haA^e been extracted, the infusion thus produced being called the tvort. This is drawn off, and cooled as rapidly as possible; then, instead of abandoning the infusion, as the Avine-maker does, to its OAvn action, the breAver mixes yeast with his Avort, and places it in vessels, each with only one aperture open to the air. Soon after the addition of the yeast, a brownish froth, Avhich is really new yeast, issues from the aperture, and falls like a cataract into troughs prepared to receive it. This frothing and foaming of the Avort is a proof that the fermen- tation is active. Whence comes the yeast which issues so cojiiously from the fermenting tub 1 What is this yeast, and hoAV did the brewer become in the first instance possessed of iti Examine its quantity before and after fermentation. The brcAvcr introduces, say 10 cwts. of yeast; he collects 40, or it may 1)0 50 CAvts. Tlie yeast has, therefore, augmented h-om torn- to five fold during tlio fermentation. Shall Ave conclude that this additional yeast has been spontaneously generated by the Avort ] Are we not rather reminded of that seed Avhicli fell into good ground, and brought forth fruit, some tliirty- fold, some sixty-fold, some an hundred-fold 1 On examina- tion this notion of organic groAvth turns out to be more than](https://iiif.wellcomecollection.org/image/b21450808_0009.jp2/full/800%2C/0/default.jpg)
