IS 13] Specific Heat of I he different Gases. 427 



current of the different gases in the preceding experiments : but 

 when a current of hot water circulates slowly in a horizontal 

 tube, it is impossible to determine its temperature exactly by 

 means of a thermometer placed in the centre of the tube, on 

 account of the unequal temperature of the different strata of 

 fluid which constitute the current. We ascertained, by experi- 

 ment, that a thermometer thus placed indicated a temperature 

 much lower than the true temperature of the current. To get 

 rid of this uncertainty, we disposed the apparatus in the manner 

 represented in fig. 9. 



The current of water which flows from the syphon, C, is 

 received into the tube, D D, which passes through a larger 

 tube, E E, kept continually filled with steam, by means of the 

 small boiler, K. The tube, D D, is soldered to another tube, 

 F F, about 03 inch in diameter.* In this tube, placed, as will 

 be seen, almost vertical, are disposed three thermometers, Nos. 

 1, 2, 3, in such a manner that the small spherical bulb of each 

 is in the centre of the tube, and at the distance of T083 inch 

 from each other. We shall see below how these thermometers 

 served to determine the temperature of the current of water at 

 its entrance into the calorimeter. The tube, F F, is cemented 

 to the horizontal tube of gins?, G G, which is cut at its end, G, 

 very near the junction, so that the bulb of the thermometer 

 No. 1, which must necessarily be in the vertical tube, that it 

 may acquire the temperature of the current of water, is, not- 

 withstanding, no farther distant from the calorimeter than the 

 first thermometer is from the third. The tube, G G, is shut 

 by a stopper, H, that no water may escape, and it is ground at 

 its extremity, G, so that by pressing it, by means of two screws, 

 against a piece of leather placed on the calorimeter, it is suffi- 

 ciently tight to prevent any water from escaping in that direc- 

 tion. The water comes out of ihe calorimeter by the tube, 

 O O O, which is capillary at its extremity, P, from which it 

 falls, drop by drop, into a graduated tube, which serves to 

 measure the rapidity of the current. The calorimeter was placed, 

 as in the preceding experiments, in a separate room, that the 

 temperature of the ambient air might be less variable. 



The same method- was always followed to determine the 

 maximum effect produced by the current of hot water. The 

 temperature of the calorimeter was in the first place raised to a 

 temperature a little below the maximum. The current of hot 

 water was then made to pass through it, and the temperature 

 narked every ten minutes. When its effects were scarcely any 

 longer greater, the thermometer stood as in the following table. 



» Thik lulu ii rrprcnentcd leparately in the plate of a larger size. 



