226 cox. 



Beat distrihuieci . 



Percentage 

 Calories, of the whole. 



(1) Heat in tlie clinker 100,0.50 10.7 



( 2 ) Heat in the chimney gases : 



(a) In the excess air admitted 336,000 36.0 



(6) In the necessary products 340,000 36..5 



(3) Heat in flue dust 2,112 0.2 



(4) Lost by imperfect combustion 12,248 1.3 



( 5 ) Evaporation of water of charge 1,446 0.2 



(6) Expulsion of carbon dioxide from carbonates 21,628 2.3 



(7) Loss by radiation and conduction 119,335 12.8 



Total 932,8X9 100.0 



• 



Richards calls attention to the fact that the maximum temperature to which 

 the 790,000 calories (the available heat of combustion) will heat the gases is 

 1,000°, while the clinker leaves the kiln at 1,200°. The difference is due to the 

 heat of combustion of the mixture. In the zone of highest temperature the 

 clinker is unquestionably heated much more than 200° above the estimated flame 

 temperature, for the heat of reaction, which is equal to 15 per cent of all the 

 heat developed, is generated in this region ; furthermore Campbell ^ has shown 

 that "the minimum temperature necessary to produce Portland cement which 

 will give a perfect pat test from fresh clinker is about 1,450° C. This tempera- 

 ture is for a minimum amount of calcium oxide. It increases with increase of 

 calcium oxide until in ordinary commercial cements it reaches 1,550°. It depends 

 somewhat on the length of time required to pass through the rotary, slow driving 

 tending to lower the temperature." 



EXPERIMENTAL. 



It is of especial importance that an examination of available Philip- 

 pine coals from the point of view of their usefulness as a fuel for 

 cement burning be undertaken. A few results are given in Table XIII. 



^'^ Campbell, E. D. : Journ. Am. Chem. Soc. (1902), 24, 991. 



