540 Accotmi of Experiments 



steam from one of the loaves in question (after it has 

 been heated to the temperature of 212°) the lol- loths, 

 equal to II 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 in- 

 genious experiments on the quantity of latent heat in 

 steam, that the quantity of heat necessary to change 

 any given quantity of water already boiling Jiot to steam 

 is about five times and a half greater than would be suffi- 

 cient to heat the same quantity of water from the tem- 

 perature 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 i lb. of pine-wood. It 

 appears, therefore, that 20 lbs. of boiling water would 

 require 52 times as much, or 5I lbs. of wood to reduce 

 it to steam. 



And if 20 lbs. of boiling water require 5I- lbs. of 

 wood, \\ of a pound of water boiling hot will require 

 lo^foo of a pound of wood to reduce it to steam. 



Df pine-wood, 

 lb. 



If now to this quantity of fuel 



we add that necessary for heating the loaf 

 to the temperature of boiling water, as 

 above determined 



This gives the total quantity of fuel neces- 

 sary for baking one of these loaves of 

 bread 



Now, as these loaves, when baked into bread, weighed 

 2 lbs. 5! loths = 2\\ lbs. each, and required in being 

 baked the consumption of iW^A of a pound of wood, 

 this gives for the expense of fuel in baking bread 



