essays-1-第77章
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The water used in making this batch of bread was 180 lbs。 15 loths。
Fourth Heating of the Oven。
This was begun 15 minutes after 12 o'clock； with 40 lbs。 of wood； and 50 lbs。 more being added at 30 minutes after 1 o'clock； the total quantity used was 90 lbs。
FIFTH BATCH。
At 1/4 before 12 o'clock； the proper quantity of leaven was mixed with the meal； and 52 quarts； or 93 lbs。 27 loths； of water put into it。This mass was prepared for kneading at 15 minutes after 4 o'clock； by the addition of 48 quarts； or 86 lbs。 20 loths； of water。 The kneading of the dough was begun at 5 o'clock； and at 30 minutes after 5 it was made into loaves； 2 1/2 lbs。 of salt having been previously added。 186 loaves being made out of this dough； they were put into the oven at 10 minutes before 7 o'clock； and taken out again at the end of one hour； when 25 loaves were weighed； and found to weigh 55 lbs。 18 loths。The quantity of water used in making the dough for this batch of bread was 180 lbs。 15 loths。
Fifth Heating of the Oven
The oven was begun to be heated the fifth time at 15 minutes after four o'clock； with 40 lbs。 of wood； and 40 lbs。 more were added at 6 o'clock； so that in this heating no more than 80 lbs。 of wood were consumed。
SIXTH BATCH。
The meal was mixed with leaven at 30 minutes after 3 o'clock； for which purpose 32 quarts； or 57 lbs。 24 loths； of water were used at 15 minutes after 7 o'clock。 This mass was prepared for kneading； by the addition of 44 quarts； or 79 lbs。 13 loths； of water； and a proportion of salt； at 19 minutes after 9 o'clock the dough was kneaded the first； and at 1/4 before 10 the second time； and in the course of half an hour 160 loaves were made out of it； which were put into the oven at 10 minutes before 11 o'clock； and taken out again at 8 minutes before 12 o'clock at midnight。
The water used in making the dough for this batch of bread was 137 lbs。 5 loths。
Sixth Heating of the Oven。
At 1/4 after 8 o'clock； the sixth and last fire was made with 40 lbs。 of wood； to which； at 15 minutes before 10 o'clock at night； 34 1/2 lbs。 more were added； so that in the last heating 74 1/2 lbs。 of wood only were consumed。
GENERAL RESULTS of these EXPERIMENTS。
The ingredients employed in making the bread in these six experiments were as follows： viz。
lbs。 loths。 Of rye meal； 1736 0 Of water； 1061 5 Of salt； 15 0 … In all； 2812 5 in weight。
Of this mass 1102 loaves of bread were formed； each of which； before it was baked； weighed 2 1/2 lbs。； consequently； these 1102 loaves； before they were put into the oven； weighed 2755 lbs。： but the ingredients used in making them weighed 2812 lbs。 5 loths。 Hence it appears； that the loss of weight in these six experiments； in preparing the leaven；from evaporation； before the bread was put into the oven；from waste； etc。amounted to no less than 57 lbs。 5 loths。
In subsequent experiments； where less water was used； this loss appeared to be less by more than one half。
In these experiments 1061 lbs。 5 loths of water were used to 1736 lbs。 of meal； which gives 61 lbs。 4 3/4 loths of water to 100 lbs。 of meal。 But subsequent experiments showed 56 lbs。 of water to be quite sufficient for 100 lbs。 of the meal。
These 1102 loaves； when baked； weighed at a medium 2 lbs。 5 1/2 loths each； consequently； taken together； they weighed 2393 lbs。 13 loths： and as they weighed 2755 lbs。 when they were put into the oven； they must have lost 361 lbs。 19 loths in being baked； which gives 10 1/2 loths； equal to 21/160 or nearly 1/8 of its original weight before it was baked； for the diminution of the weight of each loaf。
According to the standing regulations of the baking business carried on in the bakehouse of the Military Workhouse at Munich； for each 100 lbs。 of rye meal which the baker receives from the store…keeper； he is obliged to deliver 139 lbs。 of well…baked bread； namely； 64 loaves； each weighing 2 lbs。 5 1/2 loths。 And as in the before…mentioned six experiments； 1736 lbs。 of meal were used； it is evident that 1111 loaves； instead of 1102 loaves； ought to have been produced； for 100 lbs。 of meal are to 64 loaves as 1736 lbs； to 1111 loaves。 Hence it appears that 9 loaves less were produced in these experiments than ought to have been produced。
There were reasons to suspect that this was so contrived by the baker； with a design to get the number of loaves he was obliged to deliver for each 100 lbs。 of meal lessened；but in this attempt he did not succeed。
Quantity of Fuel consumed in these Experiments。
Dry pine…wood。 lbs。 loths。 In heating the oven first time； 366 16 second time； 134 16 third time； 100 0 fourth time； 90 0 fifth time； 80 0 sixth time； 74 16 Total； 845 16 Employed in keeping up a small fire near the mouth of the oven while the bread was putting into it； 34 16
Total consumption of wood in the six experiments； 880 lbs。
The results of these experiments show； in a striking manner； how important it is to the saving of fuel in baking bread； to keep the oven continually going； without ever letting it cool： for in the first experiment when the oven was cold； when it was begun to be heated； the quantity of wood required to heat it was 366 1/2 lbs。； but in the sixth experiment； after the oven had been well warmed in the preceding experiments； the quantity of fuel required was only 74 1/2 lbs。
As in these experiments 2393 lbs。 13 loths of bread were baked with the heat generated in the combustion of 880 lbs。 of wood； this gives to each pound of bread 11 1/3 loths； or 34/96 of a pound； of wood。
In the fifth experiment； or batch； 186 loaves weighing （at 2 lbs。 5 1/2 loths each） 304 lbs。 were baked； and only 80 lbs。 of wood consumed； which gives but a trifle more than 1/4 of a pound of wood to each pound of bread； or 1 pound of wood to 4 pounds of bread。
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 a
