APPENDIX. IQI 



be taken to procure average samples, since the composition 

 is apt to vary at different points of the flue ; and where com- 

 plete determinations are desired, the analysis should be 

 intrusted to an expert chemist. For approximate determina- 

 tions the Orsat* or the Hempelf apparatus may be used by 

 the engineer. 



XVIII. Smoke Observations. It is desirable to have a 

 uniform system of determining and recording the quantity of 

 smoke produced where bituminous coal is used. The system 

 commonly employed is to express the degree of smokiness 

 by means of percentages dependent upon the judgment of 

 the observer. The Committee does not place much value 

 upon a percentage method, because it depends so largely 

 upon the personal element, but if this method is used, it is 

 desirable that, so far as possible, a definition be given in ex- 

 plicit terms as to the basis and method employed in arriving 

 at the percentage. 



XIX. Miscellaneous. In tests for purposes of scientific 

 research, in which the determination of all the variables en- 

 tering into the test is desired, certain observations should be 

 made which are in general unnecessary for ordinary tests. 

 These are the measurement of the air-supply, the determina- 

 tion of its contained moisture, the determination of the 

 amount of heat lost by radiation, of the amount of infiltra- 

 tion of air through the setting, and (by condensation of all 

 the steam made by the boiler) of the total heat imparted to 

 the water. 



As these determinations are not likely to be undertaken 

 except by engineers of high scientific attainments, it is not 

 deemed advisable to give directions for making them. 



XX. Calculations of Efficiency. Two methods of defining 



* See R. S. Hale's paper on " Flue Gas Analysis," Transactions A. S. 

 M. ., vol. xvm. p. 901. 



f See Hempel on " Gas Analysis." 



