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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 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。
By an experiment； of which I intend hereafter to give an account to the Public； I found； that 20 lbs。 of ice…cold water might be made to boil； with the heat generated in the combustion of 1 lb。 of dry pine…wood； such as was used in baking the bread in the six experiments before mentioned。 Now； if 20 lbs。 of water may be heated 180 degrees； （namely from 32 to 212 degrees；） by the heat generated in the combustion of 1 lb。 of wood； 1。03 lb。 of water may be heated 157 degrees； （from 55 degrees； or temperate； to 212 degrees；） with 0。4436 of a pound of the wood。
Suppose now that rye meal contained the same quantity of absolute heat as water；as the quantity of meal in each loaf； was 1。47 lb。； it appears； that this quantity would have required； （upon the above supposition；） to heat it from the temperature of 55 degrees； to that of 212 degrees； a quantity of heat equal to that which would be generated in the combustion of 0。06405 of a pound of the wood in question。
But it appears； by the result of experiments published by Dr。 Crawford； that the quantities of heat required to heat any number of degrees； the same given quantity （in weight） of water and of wheat； （and it is presumed； that the specific or absolute heat of rye cannot be very different from that of wheat；） are to each other； as 2。9 to 1；water requiring more heat to it； than the grain in that proportion： Consequently； the quantity of wood required to heat from 55 to 212 degrees； the 1。47 lb。 of rye meal which entered into the composition of each loaf； instead of being 。06405 of a pound； as above determined； upon the false supposition that the specific heat of water and that of rye were the same； would； in fact； amount to no more than 0。02899； for 2。9 （the specific heat of water） is to 1 （the specific heat of rye）； as 0。06405 is to 0。02899。
Hence it appears； that the wood required as fuel to heat （from the temperature of 55 degrees to that of 212 degrees） a loaf of rye bread （in the state of dough）； weighing 2 1/2 lbs。； would be as follows； namely：
Of pine…wood； To heat 1。03 lb。 of water； which enters into the composition of the dough； 。。 0。04436
To heat the rye meal； 1。47 lb in weight； 。。 0。02899 Total； 0。07335 lb。
To complete the computation of the quantity of fuel necessary in the process of baking bread； it remains to determine； how much heat is required； to send off in steam； from one of the loaves in question （after it has been heated to the temperature of 212 degrees）； the 10 1/2 loths； equal to 21/64 of a pound of water； which each loaf is known to lose in being baked。
Now it appears； from the result of Mr。 Watt's ingenious experiments on the quantity of latent heat in steam； that the quantity of heat necessary to change any given quantity of water ALREADY BOILING HOT to steam； is about five times and a half greater than would be sufficient to heat the same quantity of water； from the temperature of freezing； to that of boiling water。
But we have just observed； that 20 lbs。 of ice…cold water may be heated to the boiling point； with the heat generated in the combustion of 1 lb。 of pine…wood； it appears therefore that 20 lbs。 of boiling water would require 5 1/2 times as much； or 5 1/2 lbs。 of wood to reduce it to steam。
And if 20 lbs。 of boiling water require 5 1/2 lbs。 of wood； 21/64 of a pound of water boiling hot will require 0。09023 of a pound of wood to reduce it to steam。
If now； to this quantity of fuel； 0。09023 lb。 we add that necessary for heating the loaf to the temperature of boiling water； as above determined； 0。07335 lb。 this gives the total quantity of fuel necessary for baking one of these loaves of bread； 0。16353 lb。
Now as these loaves； when baked into bread； weighed 2 lbs。 5 1/2 loths = 2 11/64 lbs。 each and required； in being baked； the consumption of 0。16353 of a pound of wood； this gives for the expence of fuel in baking bread 0。07532 of a pound of pine…wood to each pound of rye bread； which is about 13 1/4 lbs。 of bread to each pound of wood。
But we have seen； from the results of the before…mentioned experiments； that when the bread was baked under circumstances the most favourable to the econ