CANE SUGAR. 



disconnecting the bulb and filling half way up by pouring in the solution ; 

 the bulb is then placed in position, the cock g opened, the bottle lowered, 

 when the solution in the bulb rises and may be adjusted to the mark. 



The burette a is to contain the measured volume of gas ; it is first of all 

 filled with water by raising the bottle i, the three-way cock h being open to 

 the atmosphere and the cocks on the bulbs closed. The bottle containing the 

 sample of gas is then connected with the tube <?, the bottle i lowered, and 

 the cock g opened to the sample bottle, the bottle I is then raised and 

 the gas in a is forced into the burette ; a little more than 100 c.c. is forced 

 in, and then by raising the bottle i and opening the cock g to the atmosphere, 

 exactly 100 c.c. of gas may be obtained in the burette a, the water level in a 

 and i being the same. The cock g is then closed ; the bottle i is raised, and 

 the cock on b being opened, the gas is forced into the bulb b, where it is 

 allowed to remain a short time ; the cock on b is then opened, and by lowering 

 the bottle i the unabsorbed gas is drawn back into a, and after adjusting the 

 water levels in a and * the volume absorbed is read off the scale. The 

 operation is repeated to make sure that absorption is complete ; the process is 

 repeated in the other bulbs ; and the nitrogen is estimated by difference. 



What is required, however, in a factory, is not an occasional record, 

 obtained at the expense of much time and personal inconvenience, but a con- 

 tinuous record. Of the devices purchasable to this end the writer thinks the 

 1 Simance-Abady' C0 2 Recorder the most perfect; this instrument gives with 

 accuracy a continuous record of the per cent. C0 2 in the flue gases. Such a 

 record affords the superintendent a complete control over the combustion. 



Calculation of Excess of Air from Analysis of Flue 

 Oases. In air the nitrogen present occupies a volume of 3 '74 times that of 

 the oxygen. Hence if x be the percentage of oxygen, and y be the percentage 

 of nitrogen found in flue gases on analysis, this equation results : 

 Total quantity of air used __ y 



Theoretical quantity ~~ y 3 7 4# 

 If on analysis y is found to be 79% and x, 8'0, the excess of air is 



79-2 

 79-2- 29-9 = 1>598 



or 59*8 per cent, more than the theoretical minimum of air is used. 



Control from Temperature Observations. From the com- 

 position of a megass and from determinations of its thermal value it is possible 

 to calculate the temperature of the products of combustion ; thus a pound of 

 megass, which on combustion with the minimum amount of air gives -939 Ib. 

 carbon dioxide, 2'39i Ibs. nitrogen and "771 Ib. water vapour, and which is of 

 thermal value 4592 B.T.U., will have a combustion temperature over and 

 above that of the surrounding atmosphere of 



4592 =8988F., 



939 X '22 -{- 2-394 X '24 + -7 7 1 X '48 

 422 



