964 



AMERICAN FORESTRY 



that from the slower growing virgin trees of the South 

 and consequently makes better ties. 



The early settlers soon learned that chestnut did not 

 make very desirable firewood, and their descendants have 

 not forgotten the fact. Dry chestnut bums easily and 

 quickly, but it snaps and crackles, throwing out sparks 

 profusely. This makes it undesirable for the fireplace. 

 Yet it is one of the best of hardwoods for kindling, since 

 it splits easily and ignites quickly. Old chestnut rails, 

 posts, etc., frequently find an end to their usefulness as 

 kindling wood. Sometimes chestnut is used in rural dis- 



Photo by P. L. Buttrick. 

 CHESTNUT CORDWOOD USED AS A SOURCE OF TANNIC ACID 



Chestnut does not make good firewood, but it is rich in tannic acid and 

 in the South the farmers cut and haul it to the railroads for ship- 

 ment to the plants where the acid is extracted. 



tricts, where the gas range is not, as "summer wood." 

 The fact that it ignites and burns quickly renders it de- 

 sirable when a light, quick fire is wanted. 



CHESTNUT WOOD AS A SOURCE OF TANNIC ACID 



Chestnut cordwood, however, has other uses than its 

 rather precarious one of domestic fuel. It is occasionally 

 used in brick ovens, and for annealing brass, but by far 

 the largest use is as a source of tannic acid, for chestnut 

 wood is rich in that substance. Its tannin content aver- 

 ages more than 8 per cent, occasionally running as high 

 as 12 per cent. Hemlock and chestnut oak barks, for- 

 merly the chief source of the substance, run somewhat 

 higher, but their wood does not contain enough tannin 

 to pay for its extraction. Over two-thirds of all the 

 tannic acid produced in the United States is now ex- 

 tracted from chestnut wood and bark. 



It is used in the manufacture of leather and the dyeing 

 of silk. In the first case, the acid combines with the 

 albumens of the raw hides to form leather, and in the 

 second, the various coloring matters which all vegetable 

 tannins contain act as a dye on the silk fabrics. Although 

 the tannins from the various woods and barks are all 

 alike chemically, they differ in their action upon the hides 



because of the various other organic substances and col- 

 oring matters which they always contain. The tannin 

 derived from chestnut oak bark is said to give the best 

 results, both in body and color, for sole leathers. Hem- 

 lock does not impart such a good color and is used for 

 the less expensive leathers. Chestnut is largely used in 

 mixture with oak tannin for the preparation of leathers 

 of medium grade. 



The industry of extracting tannic acid from chestnut 

 wood is largely confined to the South. Chestnut grown 

 north of southern Pennsylvania does not contain a high 

 enough percentage of tannin to make its extraction profit- 

 able. The industry centers in southwestern Virginia, 

 western North Carolina and eastern Tennessee, where 

 some twenty plants, with a combined product of perhaps 

 1,000 barrels of extract per day, are at work. The proc- 

 ess is very simple. The cordwood is ground up into small 

 chips, placed in tanks and leached out by hot water. The 

 product is then evaporated to dryness or the required 

 degree of concentration. Although cordwood is gener- 



Photo by North Carolina Geological and Economic Surrey. 



INTERIOR OF A TANNIC ACID EXTRACTING PLANT 



Chips of the chestnut wood are placed in the tanks, the tops of which 

 are shown here. Hot water is then added which leaches out the 

 acid. The foam is caused by the boiling of the solution. Tannic 

 acid is used in the manufacture of leather. 



ally used, sawmill waste is sometimes employed. Wood 

 from dead timber is more in demand than from live, and 

 some of the plants in North Carolina run almost entirely 

 on wood cut from the numerous dead trees standing 

 along the eastern slope of the Blue Ridge. About 100,000 

 long cords of chestnut wood per annum are used in this 

 industry in North Carolina alone, while Tennessee uses 

 about half 'that amount, and the total production is re- 

 ported to be about 250,000 standard cords per annum. 



A few paper pulp plants in the South use chestnut in 

 the manufacture of their product. The plant which 

 uses probably the largest amount of this wood for the 

 purpose has or had a contract to supply the Government 

 with the paper for its postal cards. The tannic acid is 

 first extracted from the wood in the manner described 

 above and chips are then reduced to pulp by the soda 

 process. The chief objection to chestnut seems to be its 



