CALORIMETER. fQ^ 



fhe whole internal capacity of the vessel, which is easily known 

 wken the water does not descend below the line t n, or the 

 most elevated station of that fluid in the apparatus: and the 

 temperature must then be noted by a thermometer. A suffi- 

 cient quantity of the fuel, for the purpose of an experiment, 

 must then be taken ; for example, wood cut into small pieces, 

 and placed in the grate c d. After setting fne to it, the upper By observatioa 

 opening a h, of the stove, is to be closed, and notice taken o^quheVto^heat 

 the time employed in raising the water to a certain heat; for the water, the 

 example, that of boiling, which maybe ascertained by a t^er- j|^^^'J^°^^^^^ 

 inometer. At this period the fire is to be taken out, and the are known. 

 water and the apparatus suffered to cool to the first tempera- 

 ture at which the operation commenced. Another kind of 

 fuel; for example, pit-coal or turf is then to be disposed on the 

 grate c d, and the same observation made, after setting it on 

 fire. 



■ The greater or less rapidity with which heat is disengaged 

 from the combustibles, will be known by comparing the times 

 of the experiments respectively. 



• In order to find the diflference in the quantity or weight of — and by the 



combustible matter of different kinds, proper to produce the quantities of 



,, , , . . , , „fnel consumed 



equally-elevated temperature, it is necessary to take ot one of their economy 



the combustibles, for example, wood, a sufficient quantity, sup- is determined* 



pose one cubic foot. This is to be set on fire in the stove, 



after it hath been filled with water, and the temperature noted. 



The thermometer determines the period at which the water 



boils ; and, at this period, the fire must be extinguished, and all 



the fuel taken out which remains on the grate. And when the 



whole has been brought to its first temperature, tke process 



must be repeated with the other combustibles; for example, 



turf or pit-coal. 



If, after the operation, the quantities of combustibles made 

 use of be estimated at a medium price, it will be ea<;y to show 

 the cost of one compared with that of the other, and, conse- 

 quently, what fuel is the least expensive. 



We may also observe, that the external pipe m, may be 

 made of wood; but if it be plate-iron or copper, it will be 

 Jiroper to cover It with a number of sheets of paper, forming a. 

 thickness sufficient to prevent the ready escape of heat. 



• The pipes, k k and ??/ in, may be lengthened at pleasure, 



because 



