PAPERS ON CHEMISTRY AND PHYSICS 357 



enouslv to the center in the nsual method of procedure I 

 A brief bit of figuring will answer the query. Let us 

 recall that we are assuming a source of heat of this sort 

 equal to 500 B.t.u. per pound. Now if we start out with 

 a mass of coal at 30 deg. C, or say 100 deg. F., and 

 plan to raise the temperature of the mass to 800 deg. C, 

 or 1500 deg. F., we must provide heat enough to raise 

 the mass through 1400 deg. F. Eoughly, the specific 

 heat of coal is 50 per cent that of water, hence it will 

 require 700 B.t.u. to do the work of raising the tem- 

 perature of the mass without taking into account the 

 latent heat of vaporization for the water present. But 

 we have to our credit only 500 B.t.u. ; hence, no matter 

 how good a start we give to the reactions, they, will 

 cease to operate as soon as we pass beyond the zone of 

 external heat where that effect is lost by reason of poor 

 conductivity. As we say when attempting to start a 

 fire with green or wet wood, ''the fire goes out." 



On the other hand, if we raise beforehand the tem- 

 perature of the mass to say 300 deg. C, or 600 deg. F., 

 slightly below the point of active decomposition, the 

 work remaining to be done is now that of raising the 

 temperature of the mass through only 800 deg. F., or 

 in terms of heat units, we require only 400 B. t. u. Since 

 we assume 500 B.t.u. at our disposal and expend only 

 400, we have a slight margin to our credit which ac- 

 counts for our cumulative effect and higher tempera- 

 ture in the center at the close of the process. 



This, therefore, in a general way sets forth what we 

 believe to be the essential factors that must be taken into 

 account in the coking of high oxygen coals. 



A summarized view would indicate that the theory 

 of carbonization needs to be rewritten or revised in such 

 a manner as to cover the case of high oxygen as well as 

 low oxygen coals. That when the factors are thus un- 

 derstood and their influence properly controlled, the 

 so-called non-coking coals may be brought into the cok- 

 ing class, and that the low temperature condition is the 

 one which lends itself most readily to the carrjdng out 

 of the carbonization process. Perhaps the most import- 

 ant of all is the utilization of the exothermic property 



