BREAD. 111 
growing rapidly in fermenting wort, and setting up a similar 
fermentation in beers, bread, and other starchy matters into 
which they are introduced. Yeast consists of aggregations of 
minute cells, each cell constituting a distinct plant. It is 
employed for inducing fermentation in the making of malt 
liquors, and of distilled spirits, being also the agent in setting 
up the panary fermentation of Bread, whereby the Bread- 
substance is rendered light, porous, and spongy by its aeration 
throughout. Beer yeast may be employed as an antiseptic 
stimulant. German yeast is the ordinary yeast, collected, 
drained, and pressed until nearly dry, in which condition it can 
be kept good for several months. Patent yeast is gathered 
from a wort of malt and hops, and treated in a similar way to. 
German yeast. Leaven is called in Greek Zymee, a yeast. or 
ferment ; and hence the term “ zymotic” has come to express, 
and signify a class of diseases due to injurious ferments. There is 
now made a product, Levurine, as derived from the yeast of 
beer, possessing remarkable powers of destroying the micro- 
organisms which underlie boils, carbuncles, and abscesses. It 
is a coarse, brown powder, with a characteristic yeasty odour, 
and is given in doses of from one to three teaspoonfuls, in water, 
or milk, or in cachets. Likewise a yeast poultice is antiseptic, 
and a spoonful of fresh yeast is a good remedy for “furun- 
culosis,” or an outbreak of boils. These are immediately due 
to penetration of the skin from without by the staphylococcus 
pyogenes, and other allied micro-organisms; so that external 
germicides are called for ; but, probably, also, there is a predis- 
posing condition of the whole system at the time (the urine 
being alkaline); therefore such medicinal remedies as fresh 
lemon-juice, and orange-juice, will be likewise helpfully alterative. 
There are certain objections to be made against using yeast 
for leavening Bread, because of chemical changes which follow, 
so that some of the flour’s nourishing constituents are lost thereby. 
English baking powders are made exclusively of tartaric acid, 
with carbonate of soda, because this acid is cheaper than the 
superior cream of tartar (an article very commonly adulterated), 
which works more slowly in the baking, and leads to lighter 
bread; also arrowroot is mixed with the baking powder for 
keeping it dry, otherwise a premature chemical combination 
takes place between the acid and the alkali (particularly if at 
all meeting with damp) before the powder comes into use for 
