Page:A Practical Treatise on Brewing (4th ed.).djvu/241

Rh water, the moisture will at one time evaporate without leaving a speck of rust, while at another, a covering of rust forms upon it almost immediately. We have found this more rapid tendency to oxidation, coincident with a high state of the electrical tension of the earth, upon which variations in other processes of oxidation also appear to depend. For instance, it is a matter of general observation, that our ﬁres burn more brightly than usual, during frosty weather. A similar activity of combustion is also observed during high winds, especially when from the east or north. We have noticed the more obvious changes of the process of combustion, and also of the oxidation of iron, for two years, at the same time keeping a register of the electrical tension of the earth; and during this period we have found the more evidently bright states of combustion corresponding so uniformly with high electrical tension, that they may probably be considered as cause and effect.

From these facts we may, I think, conclude that fermentations must be greatly affected by electrical agency, and that many variations in those processes commonly ascribed to variations in the quantity or quality of the yeast employed, to temperature, &c. &c. really depend upon the changes of this more powerful and extensive influence. The very remarkable instance given by Mr. Black, page 35. of the suspension of fermentation before a