The Redwood gazette. [volume] (Redwood Falls, Minn.) 1873-1940, 1877-08-30
A Scientific Analysis Of Froth-Why
1t Ii Always White.


and women need not be ashamed to ask,
Why is froth always white or nearly white,
Whatever may he the color of the liquid
underneath it! 10 answer the question,
we shall have to determine what frOth
really is in itself, and how it is formed.
Take . filled ale-jug, or the well-known
" pewter'' of q tavern or public. house,
ami pour GU: gently into glass; scarcely
any froth is produced. Pour out the self.
same LIQUOR from the self same vessel in q
stream several inches high and you pro-
duce f0aming "head, i" which to the eye
seems to be q substance quite different
from ale or beer. Open bottle of lemon
ade or giuger-beer, of soda water or seltz-
er-water, and pour out the contents into a
glass; the formation of froth is so rapid
and abundant that the glass appears full
when it really contains but small guam
tity of liquid. Open . bottle of Bass
ale or Guinness stout; the fr0th is still
more opaque and pronounced. Look at
cup of tea or coffee soon after the sugar
has been added; there will often be seen
small covering of frUth ON the surface,
which froth, If not actually white, Is much
more 30 than the liquid beneath. Watch
the movements of the paddle-wheels of q
steamer; the water thrown back from
them is covered with foam of dazzling
whiteness, the intensity of the white in.
creasing with the rapidity of the wheels
motion.
In all these cases, and multitudes of
like kind, the froth seems to result from
agitation; . quiescent liquid seldom pre-
SCENTS symptoms of this nature. But agi-
tation alone would not do it. Surprising
it were possible for human beings to live,
or for pints of ale to exist, without afr,
there would be no such thing as froth. In
pouring out ale or other liquid, the falling
stream becomes mingled with portion Of
the atmospheric air which surrounds us;
and it also buries, as It were, the air con-
tanned in the apparently empty glass; the
result Is, mixture OF ale and air, instead
Of ale only. Under ordinary circum-
stances, liquids contain - much air Is
ti0nal quantity is expelled. But howl It
divides into minute spherical portions or
air bubbles, which ascend to the top of the
LIQUID ON account Of their levity or CON-
parative lightness.
This, however, Is not all; If It were, the
bubbles would burst directly they come to
the surface, and ffOth would mot have an
opportunity Of forming. Cohesion cones
into action, the cohesion between the par.
ticles Of every liquid. The bubbles Of
air, a. they rise from the body Of the ale,
beer or other liquid, are able 10 penetrate
between the particles; but when they ar
rive ct the surface they encounter film
of liqnid cohesive enough to restrain for
time their final escape into the atmos-
phere. Froth consists Of bubbles, each .
tiny globular portion of air, bounded on
the upper surface BY an exceedingly thin
Aim Of liquid; the bubbles retain this poo
sition and condition until the struggle
ends . victory for one of the belliger-
ents. The ascensive power Of the air
within the bubble overcomes the cohesive
power If the liquid aim or covering, and
81 the bubble bursts''-our beverage loses
its frothy head" Tho length Of time
that elapses before the air escapes BY the
bursting Of the bubble depends chle1ly on
the visibility Of the liquid. II We pour
ale into one vessel and water into another,
from equal heights, we shall find that the
former will present fr0thy surface, the
latter more instantaneous sparkling ap-
pearance; the power Of retention being
Greater In the former instance than ii the
latter. In other words, ole having great
ar specific gravity than water, and also
greater viscidity, the bubble formed has .
tkickor coating, and requires . longer
time for It's disrupture. Taking theround
OF all the . frothy headings," No flnd the
same rule prevail. In the spray from the
paddle Of Steamboat, IN the ffoth on the
surface Of beverageo, In II 1pHkles On .