1 14 CALORIFIC POWER OF FUELS. 



(0.6 to O.8 inch) inside diameter. They are filled with copper 

 oxide in small pieces, except at the front end, which has a 

 small piece of metallic copper, and at the back, where the 

 platinum boat containing the coal is placed. Usually half a 

 gram is used for a test, the coal having been previously dried 

 at 100 to 105 C. (212 to 221 F.). 



Before putting in the sample the tube is heated to redness 

 and thoroughly dried by means of a current of dry oxygen. 

 The combustion is carried on so as to allow time enough for 

 all the gas to be absorbed by the potash, during the first half 

 of the time the bubbles passing through very slowly. There 

 is no risk then of unburnt gases passing off. An iron or a 

 platinum tube may be used in place of the glass one, but glass 

 allows inspection at all times. 



An analysis should show the carbon, hydrogen, oxygen, 

 nitrogen, sulphur, ash, and moisture, and they should be so 

 given that the carbon, hydrogen, oxygen, nitrogen, sulphur, 

 and ash should equal 100 per cent, the moisture being 

 determined separately, or if preferred all but ash and moisture 

 may foot up 100, and those two be given separately. This 

 latter method is the one which is followed by many of the 

 European engineers, and will be found so in the tables given 

 at the end of this book. If possible the approximate analysis 

 should also be given. 



In determining the moisture too much care cannot be 

 taken to expel all of it. With many coals, and especially our 

 Western ones, the ordinary heating to no C. is not suffi- 

 cient. Kent, Carpenter, Hale, and others have investigated 

 this question, and find that a much higher temperature is 

 needed, and must be employed. In some cases as high as 

 140 to 150 C. may be used with safety, and such tempera- 

 tures are recommended by Carpenter, no appreciable amount 

 of volatile matter being driven off. 







