Page:A Practical Treatise on Brewing (4th ed.).djvu/56

40 well known to require any remark. It may often be owing to the same cause as the suspension of fermentation in the imbedded gyle-tuns; for when the casks are placed directly on the ground, without wooden bearers or stillions, the beer contained in them is more liable to electrical fluctuations than when the casks are better insulated.

The next case is of a different nature, and depending upon voltaic action. In 1835 some parties who had lately taken a small brewhouse near London, were surprised at the rapidity of their fermentations in certain stages; and also at the height to which the light yeasty or frothy heads rose at the same time. The author was applied to, and found that the gyle-tuns were lined with metal, which he then supposed to be lead, as is usual in such cases. A brewing was made for the purpose of ascertaining what was wrong. The worts, when gathered together, were 27 lbs. gravity per Long’s instrument, and were originally at a temperature of 58° F. in the gyle-tun, when a moderate quantity of yeast was applied. The fermentation advanced pretty regularly until about eight o’clock next evening. It had then advanced to a temperature of 62°, having a light yeasty head, and rather unusually pungent odour; it had also attenuated 4 lbs. in gravity. At six o'clock next morning it had attained a temperature of 78°, which is very unusual in so short a period. The light yeasty head