Improved Form of Coal- Calorimeter. 457 



The result o£ a number of such tests was entirely in favour 

 of the instrument, as it was found that wheu the combustion 

 was properly regulated no carbon monoxide whatever could 

 be detected. Only in one case was any real increase of 

 weight in the absorption-tube observed, and in that case the 

 amount of carbon dioxide obtained corresponded to 0*33 per 

 cent, of incompletely burnt carbon ; but in this case the 

 oxygen supply was very badly adjusted, and the combustion 

 was obviously imperfect, a considerable amount of soot being- 

 deposited ; the experiment was, however, continued in that 

 way in order to test the efficiency of the analysing arrange- 

 ment, and the result serves to show that the apparatus was 

 quite satisfactory. The author therefore feels justified in 

 stating that any loss of heat due to the escape of partially 

 burnt gases may be disregarded when the combustion is 

 properly conducted *. 



As compared with the " bomb '•' type of coal-calorimeter, 

 the present form of instrument has certain obvious advan- 

 tages. One of these is greater simplicity and cheapness ; no 

 high pressures have to be resisted, and no explosions can 

 possibly occur. Further, the combustion takes place in full 

 view, and can be watched and regulated throughout, and the 

 combustion takes place under conditions rather more like 

 those of actual practice than explosive combination under 

 great pressure. The operator has therefore a means of 

 judging the behaviour of the coal as regards coking and 

 clinkering which is not afforded by the other instrument. 

 But the strongest objection to the " bomb M instruments is that 

 in them the combustion takes place in a closed vessel having 

 thick walls ; the heat must therefore penetrate these walls 

 and be transferred to the water of the calorimeter by con- 

 duction alone, and it is probable that a considerable time 

 must elapse before the water has taken up sensibly the whole 

 of the heat. In the present instrument the water is admitted 

 at the end of the combustion to the interior of the combustion- 

 chamber, and thus has every opportunity of taking up the 

 whole heat quickly. 



"With the large bulk of water and the small rise of tem- 

 perature used in the present instrument, the radiation cor- 

 rection is very slight ; with a temperature-difference of 

 2° C. the rate of cooling is about o, 001 C. per minute, and 

 the value of the correction can be readily found in any of the 



* The thanks of the author are due to his senior assistant, Mr. W. J. 

 Jtees, for help with these experiments. 



Phil. Mag. IS. 6. Vol. 4. No. 22. Oct. 1902. 2 EL 



