As each loaf weighed 2 lbs. 16 loths when it was put into the
oven, and only 2 lbs. 5 1/2 loths when it came out of it, the
loss of weight each loaf sustained in being baked was 10 1/2
loths, as has already been observed. Now this loss of weight
could only arise from the evaporation of the superabundant
water existing in the dough; and as it is known how much heat,
and consequently HOW MUCH FUEL is required to reduce any given
quantity of water, at any given temperature, to steam, it is
possible, from these data, to determine how much fuel would be
required to bake any given quantity of bread, upon the
supposition that NO PART OF THE HEAT GENERATED IN THE
COMBUSTION OF THE FUEL WAS LOST, either in heating the
apparatus, or in any other way; but that the whole of it was
employed in baking the bread, and in that process alone.
And though these computations will not show how the heat which
is lost might be saved, yet, as they ascertain what the amount
of this loss really is in any given case, they enable us to
determine, with a considerable degree of precision, not only
the relative merit of different arrangements for economizing
fuel in the process of baking, but they show also, at the sane
time, the precise distance of each from that point of
perfection, where any farther improvements would be impossible:
And on that account, these computations are certainly
interesting.
In computing how much heat is NECESSARY to bake any given
quantity of bread, it will tend much to simplify the
investigation, if we consider the loaf as being first heated to
the temperature of boiling water, and then baked in consequence
of its redundant water being sent off from it in steam.
But as the dough is composed of two different substances, viz.
rye meal and water, and as these substances have been found by
experiment to contain different quantities of absolute heat;
or, in other words, to require different quantities of heat, to
heat equal quantities or weights of them to any given temperature,
or any given number of degrees, it will be necessary to
determine how much of each of the ingredients is employed in
forming any given quantity of dough.
Now, in the foregoing experiments, as 1102 loaves of bread were
formed of 1736 lbs. of rye meal, it appears, that there must
have been 1.47 lb. of the meal in each loaf; and as these
loaves weighed 2 1/2 lbs. each when they were put into the oven,
each of them must, in a state of dough, have been composed of
1.47 lb. of rye meal, and 1.03 lb. of water.
Supposing these loaves to have been at the temperature of 55
degrees of Fahrenheit's Thermometer when they were put into the
oven, the heat necessary to heat one of them to the temperature
of 212 degrees, or the point of boiling water, may be thus
computed.
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