JUNKER'S CALORIMETER 41 



Hugo Junker's modification of the apparatus rendered it 

 more exact. It has been used for some time in Germany 

 and in the United States. It is composed (Fig. 13) of a 

 gas-meter a, preceded by a very sensitive regulator b. On 

 leaving the meter the gas passes to a Bunsen burner c. The 

 products of combustion give up their heat to a calorimetric 

 tube d, through which regularly flows a stream of water. The 

 temperature of the gases is regulated by means of a thermom- 

 eter e. In order to keep the flow of water as regular as pos- 

 sible, it flows from the supply-tube g into a small reservoir 

 kept at a constant level governed by the tube h. The water 

 passes through i to the calorimeter and escapes at k, run- 

 ning into the glass in which it is measured or weighed. The 

 graduated tube / is to catch the condensed water from the 

 interior of the calorimeter. The thermometer m shows the 

 heat of the escaping water, and n that of the water enter- 

 ing the calorimeter. 



To calculate the calories generated during the combustion 

 proceed as follows : 



Measure the quantity of water which runs through it in 

 one minute, take the temperature of the two thermometers, 

 and note the flow of gas. The heat of combustion per cubic 

 metre of burnt gas is obtained by multiplying the volume of 

 water flowing per minute by the difference of the two temper- 

 atures and dividing the product by the gas volume burnt per 

 minute. 



Thus : 



Volume of water flowing per minute 902.3 cc. 



" <c gas burnt per minute. ..... 2500.0 cc. 



Temperature at inlet I3.IC. 



" outlet., , 27.5 C. 



002.3 X (27.5 13.1) 

 Q = - t = 5196 calories. 



