168 COUNT EUMPORD. 



bining with 2| Ibs. of oxygen, to form carbonic acid, 

 evolves heat sufficient to raise the temperature of about 

 8,000 Ibs. of water 1 C. Similarly, 1 Ib. of hydrogen, 

 in combining with 8 Ibs. of oxygen, to form water, 

 generates an amount of heat sufficient to raise 34,000 

 Ibs. of water 1 C. The calorific powers, therefore, of 

 carbon and hydrogen are as 8:34. The refined re- 

 searches of Favre and Silbermann entirely confirm 

 these determinations of Eumford " (Percy). Follow- 

 ing the experiments on combustion, we have others 

 made to determine the quantity of heat set free by 

 the condensation of various vapours, and the capacity 

 of various liquids for heat. We have also an elaborate 

 inquiry into the structure of wood, the specific gravity 

 of its solid parts, the liquids and elastic fluids contained 

 in it, the quantity of charcoal to be obtained from it> 

 and the heat generated by the combustion of wood of 

 different kinds. 



But the main object of Eumford's life and the sub- 

 ject which chiefly interested him was the practical 

 management of fire, and the economy of fuel. Eighty- 

 seven pages of the second volume of his collected works 

 are devoted to this subject. The whole of the third 

 volume is devoted to it, while a large portion of the 

 fourth and last volume is occupied with kindred ques- 

 tions. Some of those essays are rather tiresome to a 

 reader of the present day, and Eumford had a suspicion 

 that they might appear so to contemporary readers. 

 " I believe," he says, " that I am sometimes too prolix 

 for the taste of the age; but it should be remembered 

 that the subjects I have undertaken to investigate are 

 by no means indifferent to me ; that I conceive them to 

 be intimately connected with the comforts and enjoy- 

 ments of mankind; and that a habit of revolving them 



