DETERMINATION OF THE CARBON IN SMOKE !$/ 



gas containing 14.8 per cent carbonic acid, 6.7 per cent excess 

 of air, and 0.96 per cent of black. 



Saarbruck coal supplied with 155 cubic feet of air per 

 pound gave a gas having 12.8 per cent of carbonic acid, 28.5 

 per cent excess of air, and 2.03 per cent of black. 



These show that in addition to being a sign of diminution 

 in combustible gases, smoke cannot cause a notable saving 

 in fuel if such saving is accompanied by increased waste 

 gases. The sensible heat of a larger volume compensates 

 easily for the advantages resulting from the more perfect 

 combustion of the carbon. 



Bunte publishes the following determinations of black: 



Several methods have been devised for approximating to 

 the actual quantity of carbon contained in smoke. One is 

 based on the amount of soot deposited on a given surface 

 placed in the chimney. The soot deposits on the upper sur- 

 face away from the direct current. After being exposed for 

 a few hours the deposit is brushed off and weighed. Another 

 method is by using smoked glasses of different degrees of 

 opacity and ascertaining what depth of color is necessary to 

 make the smoke invisible. An improvement on this method 

 is now being worked out by one of our manufacturers of 

 optical goods, by means of which the glasses are held in a 

 tube and so arranged as to gradually produce the effect, and 

 in such way that it can be measured. 



Another method is that devised by Ringelmann, by means 

 of which the blackness of the smoke is compared with a set of 

 ruled lines, so scaled in width of line and space as to produce 

 six different gradations from smokeless through gray and 

 gray-black to dead black. He recommends the preparation 

 of cards 8 inches square, and have them suspended 50 feet 

 from the observer, at which distance the individual lines 

 become indistinct, ancl only a general tint is observable. The 

 intensity of the smoke is then compared with the cards and re- 

 corded as agreeing with card No. i, "2, or whatever it may be. 



