FERMENTATION. 533 
with this exhilarating beverage overcoming all the obstacles 
which a hot climate threw in the way of its manufacture. 
Our remote ancestors had also learned by experience that 
wine maketh glad the heart of man. Noah, we are 
informed, planted a vineyard, drank of the wine, and 
experienced the consequences. But, though wine and beer 
possess so old a history, a very few years ago no man knew 
the secret of their formation. Indeed, it might be said 
that until the present year no thorough and scientific 
account was ever given of the agencies which come into 
play in the manufacture of beer, of the conditions necessary 
to its health, and of the maladies and vicissitudes to which 
it is subject. Hitherto the art and practice of the brewer 
have resembled those of the physician, both being founded 
on empirical observation. By this is meant the obser- 
vation of facts, apart from the principles which explain 
them, and which give the mind an intelligent mastery 
over them. The brewer learned from long experience the 
conditions, not the reasons, of success. But he had to 
contend, and has still to contend, against unexplained per- 
plexities. Over and over again his care has been rendered 
nugatory; his beer has fallen into acidity or rottenness, and 
disastrous losses have been sustained, of which he has been 
unable to assign the cause. It is the hidden enemies 
against which the physician and the brewer have hitherto 
contended, that recent researches are dragging into the 
light of day, thus preparing the way for their final exter- 
mination. 
Let us glance for a moment at the outward and visible 
signs of fermentation. A few weeks ago I paid a visit to 
a private still in a Swiss chalet; and this is what I saw. 
In the peasant's bedroom was a cask with a very large 
bunghole carefully closed. The cask contained cherries 
which had lain in it for fourteen days. It was not entirely 
filled with the fruit, an air-space being left above the 
cherries when they were put in. I had the bung removed, 
and a small lamp dipped into this space. Its flame was 
instantly extinguished. The oxygen of the air had entirely 
disappeared, its place being taken by carbonic acid gas.* 
*The gas which is exhaled from the lungs after the oxygen of the 
air has done its duty in purifying the blood, the same also which 
effervesces from soda water and champagne. 
