190 APPENDIX. 



coal one-half inch or more in diameter are to be picked from 

 the refuse and deducted from the weight of coal fired. 



XVI. Calorific Tests and Analysis of Coal. The quality 

 of the fuel should be determined either by heat test or by 

 analysis, or by both. 



The rational method of determining the total heat of 

 combustion is to burn the sample of coal in an atmosphere of 

 oxygen-gas, the coal to be sampled as directed in Article XIV 

 of this Code. 



The chemical analysis of the coal should be made only by 

 an expert chemist. The total heat of combustion computed 

 from the results of the ultimate analysis should be obtained 

 by the use of Dulong's formula (with constants modified .by 

 recent determinations), viz., 



/ O 



14600 C + 620OO V H Tr- 

 ill which C, H, and O refer to the proportion of carbon, 

 hydrogen, and oxygen respectively, and determined by the 

 ultimate analysis.* 



It is recommended that the analysis and the heat test be 

 each made by two independent laboratories, and the mean of 

 the two results, if there is any difference, be adopted as the 

 correct figures. 



It is desirable that a proximate analysis should also be 

 made to determine the relative proportions of volatile matter 

 and fixed carbon in the coal. 



XVII. Analysis of Flue-gases. The analysis of the flue- 

 gases is an especially valuable method of determining the 

 relative value of different methods of firing, or of different 

 kinds of furnaces. In making these analyses great care should 



* Favre and Silbermann give 14544 B. T. U. per pound carbon; Berthe- 

 lot 14647 B. T. U. Favre and Silbermann give 62032 B. T. U. per pound 

 hydrogen; Thomson, 61816 B. T. U. 



