688 



AMERICAN FORESTRY 



tion of the English oak. Acorns from the white oak, 

 chestnut oak, and blackjack oak were planted in a box in 

 sphagnum moss on September 12, 1912, and the results 

 recorded on October 22, 1912. Two series of green 

 acorns were sown. One set had a portion of the shell 

 .removed, exposing the embryo. The other set was 

 planted with the acorn shells unimpaired. There was a 

 slight advantage in the rate of germination of the cut 

 acorns, as contrasted with the uncut. Practically all of 

 the green acoms of the chestnut oak, blackjack oak and 

 white oak germinated without passing through a dormant 

 period. In fact, the dormant period is not necessary for 

 acorn germination, although Sachs ' has maintained that 

 even under the most favorable conditions dormant periods 

 occur in the lives of plants and although the external 

 factors are favorable, every extremely perceptible vital 

 manifestation ceases, and it is only after more months of 

 rest that the growth commences anew, and this frequently 

 under circumstances which appear far less favorable, 

 especially at a conspicuously lower temperature. This 

 has evidently been the philosophy under which foresters 

 have layered their nuts and acorns for their preservation 

 in a viable condition through the winter. The practice 

 under these conditions has been described previously as 

 practised by Dr. Rothrock. 



The experiments narrated above show that a rest 

 period is not essential for the germination of acorns, but 

 that by taking immature acorns, whose embryo has not 

 ceased to grow, and planting them, the period of growth 

 is maintained without cessation, or without a rest period, 

 and the result is the elongation and growth of the embryo 

 into a young seedling plant, as fully demonstrated by 

 the figures (H-M). 



The germination capacity of so-called unripe seeds 

 does not seem to have been appreciated by foresters and 

 gardeners, who layer their tree seeds in boxes of sand, 

 kept slightly moist, and kept in a cool, protected place 

 over winter. That the acorns can be planted, while green, 

 in protected frames and carried over the winter in the 

 frame, or cool greenhouse, in the actively growing con- 

 dition, and planted out in the spring, should be a boon 

 to the forester, who has been troubled with the successful 

 preservation of the acorns over winter. A practical trial 

 of this new method on a large scale should be made at 

 some forest station in the United States. 



1 Sachs. Julius. The Physiology of Plants. 350. 



FUEL VALUE OF WOOD 



THE fuel value of 2 pounds of wood is roughly 

 equivalent to that of 1 pound of coal. This is 

 given as the result of certain calculations now 

 being made in the Forest Service laboratory, which show- 

 also about how many cords of certain kinds of wood 

 are required to obtain an amount of heat equal to that 

 in a ton of coal. 



Certain kinds of wood, such as hickory, oak, beech, 

 birch, hard maple, ash, elm, locust, longleaf pine, and 



cherry, have fairly high heat values and only one cord 

 of seasoned wood of these species is required to equal 

 one ton of good coal. 



It takes a cord and a half of shortleaf pine, hem- 

 lock, red gum, Douglas fir, sycamore, and soft maple to 

 equal a ton of coal, and two cords of cedar, redwood, 

 poplar, catalpa, Norway pine, cypress, basswood, spruce, 

 and white pine. 



Equal weights of dry, non-resinous woods, however, 

 are said to have practically the same heat value regard- 

 less of species, and as a consequence it can be stated as a 

 general proposition that the heavier the wood the more 

 heat to the cord. Weight for weight, however, there is 

 very little difference between various species ; the average 

 heat for all that have been calculated is 4600 calories, or 

 heat units, per kilogram. A kilogram of resin will develop 

 9400 heat units, or about twice the average for wood. As 

 a consequence, resinous woods have a greater heat value 

 per pound than non-resinous woods, and this increased 

 value varies, of course, with the resin content. 



The available heat value of a cord of wood depends 

 on many different factors. It has a relation not only to 

 the amount of resin it contains but to the amount of 

 moisture present. Furthermore, cords vary as to the 

 amount of solid wood they contain, even when they are 

 of the standard dimension and occupy 128 cubic feet of 

 space. A certain proportion of this space is made up 

 of air spaces between the sticks, and this air space may 

 be considerable in a cord made of twisted, crooked, and 

 knotty sticks. Out of the 128 cubic feet, a fair average 

 of solid wood is about 80 cubic feet. 



It is pointed out, however, that heat value is not the 

 only test of usefulness in fuel wood and since 95 per cent 

 of all wood used for fuel is consumed for domestic pur- 

 poses, largely in farm houses, such factors as rapidity of 

 burning and ease of lighting are important. Each sec- 

 tion of the country has its favored woods and these are 

 said to be, in general, the right ones to use. Hickory, 

 of the non-resinous woods, has the highest fuel value 

 per unit volume of wood, and has other advantages. It 

 burns evenly, and, as housewives say, holds the heat. The 

 oaks come next, followed by beech, birch, and maple. 

 Pine has a relatively low heat value per unit volume, 

 but has other advantages. It ignites readily and gives 

 out a quick, hot flame, but one that soon dies down. 

 This makes it a favorite with rural housekeepers as a 

 summer wood, because it is particularly adapted for hot 

 days in the kitchen. 



The fuel qualities of chestnut adapt it particularly to 

 work in brass foundries, where it gives just the required 

 amount of heat and it is therefore in favor. Coastwise 

 vessels in Florida pay twice as much for Florida button- 

 wood as for any other, because it burns with an even heat 

 and with a minimum amount of smoke and ash. 



The principal disadvantage of the resinous pines is 

 their oily black smoke. 





