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tation of a solution of sugar. Yeast, which by 
continued washing has entirely lost the property 
of inducing fermentation, regains it when its 
putrefaction has recommenced, in consequence of 
its being kept in a warm situation for some time. 
Yeast and putrefying animal and vegetable mat- 
ters act as peroxide of hydrogen does on oxide 
of silver, when they induce bodies with which 
they are in contact to enter into the same state 
of decomposition. The disturbance in the at- 
traction of the constituents of the peroxide of 
hydrogen effects a disturbance in the attraction 
of the elements of the oxide of silver, the one 
being decomposed on account of the decomposi- 
tion of the other. Peroxide of hydrogen is 
rapidly decomposed in contact with moist fibrin 
of blood, an animal substance in a continuous 
state of decomposition; the oxygen which it 
contained, in addition to that necessary to form 
water, escapes with violent effervescence. Now 
if we consider the process of the fermentation of 
pure sugar, in a practical point of view, we meet 
with two facts of constant occurrence. When 
the quantity of yeast is too small in proportion 
to that of the sugar, its putrefaction will be 
completed before the transformation of all the 
sugar is effected. Some sugar here remains un- 
decomposed, because the cause of its transforma- 
tion is absent, viz., contact with a body in a. 
state of decomposition. But when the quantity 
of yeast predominates, a certain quantity of it 
remains after all the sugar has fermented, its 
decomposition proceeding very slowly, on account 
of its insolubility in water. This residue of yeast 
is still able to induce fermentation, when intro- 
duced into a fresh solution of sugar, and retains 
the same power until it has passed through all 
the stages of its own transformation. Hence a 
certain quantity of yeast is necessary in order to 
effect the transformation of a certain portion of 
sugar, not because it acts by its quantity in in- 
creasing any affinity, but because its influence 
depends solely on its presence, and its presence 
is necessary, until the last atom of sugar is de- 
- composed.” 
Yeast for making bread, as good as any which 
can be obtained from brewers, or better, may be 
made in any of the three following ways. Mash 
about two quarts of malt in a gallon of water; 
and let it stand about two hours,—then skim it 
off into another small tub,—and when it is suffi- 
ciently cool, add a table spoonful of yeast. This 
process is the same as brewing, only without 
adding hops or boiling the wort; and it must be 
repeated whenever a fresh supply is wanted,— 
always keeping a little of the former yeast to 
make the next ferment. ‘The quantity produced 
is sufficient for a large baking. If the weather 
be very cold, the tub may require to be placed 
near the kitchen fire in order to set up the fer- 
mentation. Besides the yeast which rises to the 
surface of the fluid, some will fall to the bottom. 
—Another :—Boil half a pound of hops for two 
—— 
YEAST. 
‘become blood-warm, then add one gallon of yeast 
187 
hours in ten gallons of water; strain the liquid 
into a tub, stir in half a pound of ground malt, 
mix it well, stir it occasionally till the liquid 
obtained from a brewer or preserved from your 
own last making, add also two pounds of flour, 
mix the whole well together, allow the mixture 
to ferment during eight hours, and then stir it 
up and strain it into a barrel, and keep it as 
nearly as possible air-tight. The produce will 
amount to about eight gallons, and will have a 
medium appearance between that of thin brewer’s 
yeast and thick beer, and, if properly made and 
properly used, will be found to surpass any 
brewer’s yeast for the purposes of baking. If 
only a gallon or two be wanted, it may be made 
from proportionate quantities of the ingredients; 
and if put into a stone bottle, tightly corked, 
and placed in a cool situation, it will keep good 
for a long time.—Another:—Boil one ounce of 
hops in four quarts of water till the hops fall to 
the bottom of the pan; strain the liquid, let it 
stand till blood-warm, add to it six ounces of 
flour and five of sugar, set the mixture near the 
fire, stir it frequently, and at the end of forty- 
eight hours add to it four pounds of boiled and 
finely bruised potatoes. The yeast will be ready 
next day ; and if properly bottled and stored will 
keep good during a month. See the articles 
Breap and FERMENTATION. | 
Yeast is both an external and an internal 
therapeutic. When applied to foul and sphace- 
lating ulcers, in union with farinaceous sub- 
stances in the form of poultices, it corrects fetor, 
assists sloughing, and renders the purulent se- 
cretion healthful; and when administered inter- 
nally to the human subject, in doses of about 
half an ounce every two or three hours, in com- 
bination with sugar or porter or wine, it acts as 
an antiseptic and a tonic, and has been thought 
particularly serviceable in putrid fevers. 
Refuse or putrefied yeast, in a state no longer 
fit for any of its proper purposes as a ferment, 
and when either made up with other ingredients 
into a solid compost or diluted with water and. 
applied in the way of liquid manure, is one of 
the most powerful of known fertilizers, and, even 
when used in very small quantity, produces great 
effects on grass-lands, turnips, cabbages, cauli- 
flowers, oleaginous crops, roses, pelargoniums, 
dahlias, and many other crops and plants which 
require rich nitrogenous manure. 
YELLOW BIRD’S NEST. See Birp’s Nust 
and Monorroprz. 
YELLOW-HAMMER, — Hinberiza Citrinedla. 
A well known British bird of the conirostrous 
family of Passerine. It is also called the yellow | 
bunting, the yoyt, and the yoldren. Its head | 
and all the under parts of its body are of a pale | 
yellow or straw colour; the hinder part of its 
neck is tinged with green ; its breast is orange- 
red; and the inner edge of the two external 
quills of its tail is white. It builds its nest most 
a 
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