TEMPERATURE OF THE WASTE GASES. !$! 



out at B* As soon as this occurs no further change of suc- 

 tion takes place in the chamber C, providing the gas entering 

 at A and passing out at B be maintained at the same tem- 

 perature. 



If from the constant stream of gas, while flowing through 

 chamber C, one of its constituents is continuously removed by 

 absorption, a reduction of volume will take place in chamber 

 C and cause an increase in suction, and consequently a de- 

 crease in the effective suction in C' . Hence the velocity of 

 the gas through A will increase, and the velocity through B 

 will decrease, until the same quantity of gas enters at A as 

 is absorbed by the reagent, plus that which passes out at 

 aperture B. 



Thus every change in the volume of the constituents we 

 are absorbing from the gas causes a corresponding change of 

 suction in the chamber C. 



The apparatus is connected with a regulator, a manom- 

 eter, and automatic recording register. 



TEMPERATURE OF THE WASTE GASES. 



As in analyzing coal, cinders, and gases we must have 

 average samples, so in treating of waste gases we need average 

 temperatures. It is not enough to take the temperature 

 occasionally with the thermometer; it varies too much from 

 time to time, even if the readings are taken frequently. We 

 must have some method of obtaining the average temperature 

 of the gas current, and this can be accomplished by means of 

 a heat reservoir introduced into the flue. 



For this purpose one was devised by Scheurer-Kestner of 

 a type which has been repeatedly copied and modified. It 

 consists of an iron tube, bb (Fig. 39), placed in the flue so 

 that the upper end, covered with an insulating material, is let 

 into the wall to about one half its thickness, the remainder 

 hanging free in the flue. This tube is filled with paraffin, 



