Canadian Forestri] Journal, April, 1918 



1633 



consist of the same substance and 

 one species differs from another 

 chiefly by the way this is arrani^t^" 

 in the wood structure. Since ^.i 

 woods do consist chiefly of the one 

 substance, the Calorific Values of 

 all of them must be the same. 

 Measurements of the Calorific Value 

 show that 1 pound of perfedlij drij 

 wood yields 8,220 B.T.U. For' com- 

 parison it may be stated that 1 

 pound of good hard coal yields 

 about 12,000 to 13,000 B.T.U. and 

 poor coals go very much lower. 

 Perhaps it would be better to com- 

 pare these in terms of cords and 

 tons. One cord of air dried maple 

 or birch will contain about 3,250 

 lbs. of dry wood and about 720 

 lbs. of moisture. Its heating value 

 will then be 



3,250 X 8,220—26,715,000 B.T.U. 

 less 1,220 X 720— 878,400 B.T.U. 

 giving a net heating value of 25,836, 

 600 B.T.U. 



A ton of coal gives a net heating 

 value of 



2,000 X 13,000—26,000,000 B.T.U. 

 These two values are very nearly equal 

 so that we can say that one cord 

 of well dried hardwood {beech, birch 

 or maple) is equal to one ton of good 

 hard coal. Other woods have heat- 

 ing values in proportion to their 

 weight per cubic foot. 



A Guide to Values 



The following table shows the 

 number of cords of various common 

 woods required to equal 1 cord 

 of well dried hardwood or 1 ton 

 of coal. 



Ash 1. 10 cords. 



Basswood 1.70 



Beech 1.00 " 



Birch 1.00 " 



Butternut 1.60 



Elm 1.00 " 



Maple 1.00 " 



Oak, red 0. 97 " 



Oak, white 0.93 " 



Poplar 1.55 " 



Cedar 2. 10 " 



Douglas fir 1.20 " 



Balsam fir 1. 80 cords. 



Hemlock 1.60 



Jack pine 1.50 



Spruce 1. 60 " 



Tamarack 1. 15 " 



Split Wood is Best 



This table gives approximately 

 the heating value of well air dried 

 cordwood but the amount of drying 

 is important. Wood piled with the 

 bark on dries very slowly so that 

 when purchasing wood split wood 

 is to be preferred to small sized 

 round wood since the latter will 

 probably not be so dry and will 

 include more bark and rotten wood 

 which has little heating value. 



Some other consideration may at 

 times be as important as the actual 

 heating value of the wood. For 

 instance, the ease of lighting is 

 to be considered if the wood is 

 wanted only for kindling or for 

 a quick fire in the kitchen range 

 in the summer. Cedar and pine 

 are especially good for this pur- 

 pose. For an open fireplace the 

 hardwoods are best. Spruce makes 

 a very "crackly" fire which is some- 

 times an attraction but there is 

 always some danger that a spark 

 may be thrown out of the fire to 

 the detriment of clothing or th 

 rug. 



A Comparison of Ashes 



Another point worth bea" 

 mind in connection with the 

 of wood in place cf cq 

 difference in the amo' 

 produced. A cord of ' 

 make only about 

 ashes while a ton 

 makes from 20' 

 judging from 

 coal coming 

 past winte' 

 mount V 

 lots W'' 

 espec' 

 Th 



