JIOIT Oi? 1 STUM >D MD L( PINE .0. Donk, C.i. Snattuok .1). tarsia 11 . , . U 3ul. 1005 Dec. 1921 - Forestry. Main Lihrai s >, , ysim H UNITED STATES DEPARTMENT OP AGRICULTURE BULLETIN No. 1003 Contribution from the Bureau of Chemistry W. G. CAMPBELL, Acting Chief And the University of Idaho, A. H. UPHAM, Washington, D. C. December 5, 1921 THE DISTILLATION OF STUMPWOOD AND LOGGING WASTE OF WESTERN YELLOW PINE By M. G. DONK, Assistant Chemist Leather and Paper Laboratory, Bureau of Chemistry C. H. SHATTUCK, Professor of Forestry, and W. D. MARSHALL Research Fellow, Forestry Department, University of Idaho CONTENTS Pag? Importance of western yellow pine . . 1 Distribution of western yellow pine . . 2 Purpose of investigation 13 Taking samples 15 Distillation of samples 22 Crude products of retort distillation . . 31 Products obtained ih refining crude turpentine 37 Calculation of yields of refined turpen- tine and pine oil ., 41 Commercial distillation processes ... 43 Page Feasibility of distilling western yellow Pine 46 Relation of wood distillation to land clearing 51 Small, semi-portable wood-distilling plants 53 Use of oil for ore flotation 54 Refining crude wood turpentine .... 56 Summary 67 Literature cited 69 WASHINGTON GOVERNMENT PRINTING OFFICE 1921 UNITED STATES DEPARTMENT OF AGRICULTUR BULLETIN No. 1003 Contribution from the Bureau of Chemistry W. G. CAMPBELL, Acting Chief And the University of Idaho, A. H. UPHAM President Washington, D. C. December 5, 1921 THE DISTILLATION OF STUMPWOOD AND LOGGING WASTE OF WESTERN YELLOW PINE. By M. G. DONK, Assistant Chemist, Leather and Paper Laboratory, Bureau of Chemistry, C. H. SHATTUCK, Professor of Forestry, and W. D. MARSHALL, Research Fellow, Forestry Department, University of Idaho. 1 CONTENTS. Importance of western yellow pine Distribution of western yellow pine- Purpose of investigation Taking samples Distillation of samples Crude products of retort distillation- Products obtained in refining crude turpentine Calculation of yields of refined tur- pentine and pine oil Page. 2 13 15 22 31 37 41 Page. Commercial distillation processes 43 Feasibility of distilling western yel- low pine 46 Relation of wood distillation to land clearing- 51 Small, semi-portable wood-distilling plantjs 53 Use of oil for ore flotation 54 Refining crude wood turpentine 56 Summary 67 Literature cited 69 IMPORTANCE OF WESTERN YELLOW PINE. Western yellow pine (Pinus ponderosa) is the most widely dis- tributed of the western commercial softwoods (4, 10) 2 (fig. 1). The Forest Service estimates the amount of standing timber of this species to be approximately 335,000,000,000 board feet, or more than that of any other species except Douglas fir (6). The reported cut for this species for 1917 was 1,862,914,815 board feet. This repre- sents an area of more than 350,000 acres of land annually cleared and left covered with stumps after logging operations. About one- third of this is within the national forests and is generally of little value for agriculture, because of the roughness of the land. Much of the remaining two-thirds, however, is valuable for crops. 1 The sections on the importance and distribution of the western yellow pine are by C. H. Shattuck. The report of the investigation is by M. G. Donk. 2 The numbers in parenthesis throughout this bulletin refer to the bibliography on page 69. 60953 21 1 ^96093 2 BULLirirc: ; rv.: m$rA.Kt"rtr.NT or Acuirri/rrnr.. Removing the stumps is arduous Mini costly (8), and so far they have leen considered to be worthless after removal. Any process which may serve to reduce the cost of clearing the laud or lead to the discovery of a profitable use for the stumps is, therefore, worthy of careful consideration. Observations on the methods of utilizing the more resinous portions of the yellow 7 pine of the South in the manufacture of wood-distillation products su^c-ted the possibility that the western species might serve the same purpose, as these trees, especially the stumps, are often quite resinous. It is well known that western yellow pine was used in California as a profitable source of turpentine during the Civil War (13). In speaking of turpentine obtained from western yellow pine. Schorger (7) says: "There is no reason to suppose that both the California and the Ari/ona oils will not serve the purposes for which ordinary turpentine is commonly used." According to Betts (2), nearly as much turpentine and rosin was obtained from western yellow pine as from the pines of the Southeast. Wenzell (5) states that the odor, specific gravity, and boiling point of oleoresin from Pinus ponderosa correspond with those of the common oil of turpentine. It is there- fore reasonable to suppose that turpentine operations in the large tracts of virgin pine timber in the West will be undertaken within a few years, because of the rapid cutting of the yellow pine of the South. DISTRIBUTION OF WESTERN YELLOW PINE. For convenience the chief areas of western yellow pine may be grouped as follows : (1) Arizona and New Mexico. (2) California. (3) Oregon jind Washington. (4) Idaho, Montana, and Utah. (5) Colorado, South Dakota, and Wyoming. For want of accurate data, no estimates covering the quantities of this species annually cut for fuel and uses other than for lumber are given, although this amount is known to be considerable. Neither is any account taken of the distillation material to be derived from "fat" limbs and "pitchy" butts. The estimates of stands, and therefore of stumps, in many of the States are low because the results of the cruises of much privately owned timber were not obtainable. The problem of the better utilization of this species is by no means confined to Idaho. Tables 2 to 1-J and the map (fig. 1) furnish con- clusive proof of the enormous quantities of yellow-pine stumps to be had in several Western States. It will not be profitable to work up by distillation methods any but the more resinous of the stumps, " fat " limbs, and " pitchy " butts. A complete field survey of each DISTILLATION 3 region to determine the stand or number of rich resinous stumps and the practicability of profitable distillation must be left to those in FIG. 1. Geographic distribution of Pinus ponderosa. the various regions who plan to enter the field of wood-distillation from a commercial standpoint. Such a survey, however, should al- ways be made before undertaking distillation in any section. ;/ P, PKARTJVfENT OF AGRICULTURE. ARIZONA AND NEW MEXICO. Total area in the national forests acres__ * 4, 571, 425 Total stand in the national forests board feet 17,002,000,000 Total annual cut (1917) , do 154, 2J)7, 815 Total area annually cleared (if clear cutting is em- ployed) acres 38, 574 Total annual volume of stumpwood cords * 77, 148 For average stands the number of trees over 18 inches varies from 85 to 12, and the number of those over 24 inches varies from 7 to 9 ; heavy stands have from 12 to 30 trees 18 inches and over, and from 11.5 to 20 trees 24 inches and over. Since 500 board feet is a liberal average volume for a yellow-pine tree 22 inches in diameter at breast height, or 24 inches on the stump (3, 13), stands of 5,000 feet an acre would contain 10 trees averaging 24 inches on the stump. The average stand over Arizona and Xew Mexico being approximately 4,000 board feet for all the area covered with yellow pine, the average number of 24-inch stumps an acre would be 8. Many thousands of acres show stands above 5,000 feet, the actual number of trees 24 inches and over being from 10 to 15 to the acre. It is evident, therefore, that this region has future possibilities from the standpoint of wood by-products, if it is found that a fair percentage of the stumps are rich in resin. No account has been taken of the material obtainable from "fat" limbs or "pitchy" butts, and only the timber on national forests, where accurate cruises have been made, is here considered. Though no figures are avail- able for the timber on private holdings, Indian lands, and the pub- lic domain, it is known that these areas are quite extensive, and many of the stands are average or better. CALIFORNIA. Total area acres 10,000,000 Total stand board feet__ 85,000,000,000 Total annual cut (1917) do 154,297,815 Total area annually cleared ( if rlcar cutting is employed) acres 38,574 Total annual volume of stumi\vood cords 4 77, 148 California has about 10,500,000 acres of commercial yellow pine, with from 85,000,000,000 to 90,000,000,000 board feet, or from 8,000 to 12,000 board feet an acre. Trees above 12 inches in diameter, breast high, have an average diameter of 38 inches, or approximately 41 inches on the stump, for which reason the yellow-pine trees of Cali- fornia are the largest known. Since the species usually grows in mixed stands, the number of trees an acre is low. The pitch content, however, is higher than that in any other section. As the yellow pine in California is the heaviest known (Table 1), the amount of "pitchy" wood can safely be takvn as average or better. National forests only. ' 1 '<>r roducing factors s**' Table d. DISTILLATION OF STUMPWOOD. TABLE 1. Stands of western yellow pine in California, Oregon, and Washing- ton, ivith reduction factors for various volumes and diameters of trees and stumps* Diameter. Average volume Reduc- Reduc- tion Breast high. tion, breast height to Stump high.* Of trees. Of stumps. units for different volumes stump height. and di- ameters. Inches. Inches. Inches. Bd.ft. Cords. 22 2 24 500 0.25 1 23 2 25 600 24 2 26 750 .375 1.5 25 2 27 850 26 2 28 950 26.5 2 28.5 1,000 .5 2 27 2 29 1,150 28 2.5 30.5 ,250 .625 2.5 29 2 5 31 5 350 30 2 5 32.5 ,425 30.5 2.5 33 ,500 .75 3 32 2 5 34.5 ,600 32 5 2 5 35 ,750 3.5 33 2.5 35.5 ,850 .875 33 5 2 5 36 ,925 34 3 37 2,000 1 4 35 3 38 2,150 36 3" 39 2,250 1.125 4.5 37 3 40 2,400 38 3 41 2,500 1.25 5 39 3.5 42.5 2,600 40 3.5 43.5 2,750 .375 5.5 41 3.5 44.5 3,000 .5 6 41.5 3.5 45 3,250 .625 6.5 42 3.5 45.5 3,500 .75 7 43 3.5 46.5 3,750 .875 7.5 44 3 5 47 5 3 900 45 4 49 4,000 2 8 1 This working table must be adapted by the user to meet the variations from the normal stand as they are found to occur. The volumes inboard feet represent close approximations of the averages of all obtainable volume tables for the regions named. The volumes in cords are taken from measurements of corded stumpwood in various regions, and are as conservative, when the wood is split for the retort, as those used for volume, B. M. The height of the stump is here assumed to be 18 inches. For higher stumps the diameter would be duced according to the scale, as given in columns 5 and 6. TABLE 2. Sample cruises of California, yellow pine from different parts of the State, with volume and acre equivalent in number of stumps of various diam- eters required to produce the given yields (area covered, 6,400 acres, average xtand, or slightly better). 1 Location. Volume per acre. Number stumps. Per cent total stand. 24- inch. 28.5- inch. 37- inch. Eldorado T 8 N R 15 E, sec. 35 Bd.ft. 10, 082 10, 501 18,236 12, 253 12, 444 9,503 5,870 10, 518 17,163 12, 276 20.00 21.00 36.40 2450 24.88 19.00 11.74 21.02 34.32 24.55 10.00 10.50 18.20 12.25 12.44 9.50 5 87 10.51 17.16 12.27 5.00 5.25 9.10 6.12 6.22 4.80 3.92 5.25 8.58 6.11 83.6 64.7 46.4 68.5 87.6 26.9 71.6 83.4 72.1 47.4 Lassen, T 25 N, R 14 E, sec. 24 Lassen, T27N, R 10 E sec. 5 Lasen T 32 N R 8 E sec Modoc, T 46 N, R 15 E, sec. 32.. . Plumas T 23 N R 9 E, sec. 5 Sequoia, T 13 S, R 19 E, sec. 19 Sierra, T 5 S, R 21 E, sec 18. Sierra, T 6 S, R 24 E, sec. 27 Stanislaus, T 4 N R 18 E, sec. 17 . Average for 6,400 acres 11,884 23.75 11.88 5.94 64.5 1 Estimates furnished by T. D. Woodbury, assistant district forester, San Francisco, Calif. If the stump- high diameters were used instead of those'breast high, a large number of trees would be included in the 24-inch class, as many trees measuring 22 inches and over, breast high, would come within the 24-inch class if measured on the stump. BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. TABLE 3. Practical application of Table 1. Vol- Trees 24 Aver- cedt 1 Humps ] ^er acre < jquivale. at. Location. Area. per acre. inches and over. ameter stump high. 24- inch. 33- inch. 35- inch. 43- inch. 49- inch. T 4 N RISE, sec. 19. Acre*. 7 Ed.it. :<:> 4<*) 9 1 Inches. 48 70.9 23.6 20.3 12.8 8.8 T 9 S R 24 E sec 2 16 11) 7(K) i 1'. 34.5 21 4 7.1 6.1 T 9 N. R 24 E, sec. 1. . 16 9 74i 5.5 32.0 19.5 6.5 T 8 N R 23 E sec. 15 16 11 (KM) 4 43.5 22.0 7.3 4.0 T 4 N R 21 E sec 32 16 13 112 4.7 43 5 26 2 8.7 4.7 TlOandllS R25and36E 17, 495 12' 200 33.0 24.4 8 1 T 4 and 5 S, R 20 and 21 E ... i, ;!.):( 6.710 32.5 13 4 4.5 T 3 and 4 S, R 19 E 3 820 6 770 33.5 13.5 4,5 T 7 S R 22 E 300 8 139 33.0 16 2 5 4 Volume equivalents: Lumber (board feet).. 500 1 000 1 500 2 000 2 500 3 000 3.500 4.000 .25 50 .75 1.0 1.25 1.50 1.75 2.00 OREGON AND WASHINGTON. Oregon. Washington. Total area acres 10 000 000 3 400,000 Total stand... board feet 70, 000, 000, 000 17, 000, 000, 000 Volume per acre do 7 000 5,000 Total annual cut (1917) do.... 470,488,000 220,924,000 Total area annually cleared (1917) acres 67 212 44,185 Total annual volume of stumpwood cords.. 235,244 110,462 Western yellow pine occurs on about 14,000,000 acres in Oregon, practically a quarter of the State and half of its timbered land. Of this area about 10,000,000 acres may be classed as commercial forest, the estimated stand amounting to 70,000,000,000 board feet, or an average of 7,000 board feet an acre, interforest waste areas in- cluded (6). TABLE 4Rcprcsentatir( irrxtern yelloiv-vim stands in Oregon. Location. Area. Average number of trees. Per cent of stand. 12-inch and over. 18-inch and over. 24-inch and over. Near Austin and Whitney Acres. 258 44 30 159 25.42 34.57 32.00 25.37 18.97 21.34 21.23 19.85 13.78 15.48 15.10 15. 41 83.2 87.3 1 99.5 75.2 Near Looldngglass Creek Near Embody Klamath Lake Section. . . Table 4 shows average stands of Oregon yellow pine more or less mixed with other timber. Pure stands contain a proportionately greater number of trees. In cruises made by the United States ( " "logical Survey, on pure, heavy stands of yellow pine near Kich- land, the average number of trees above 12 inches on strip acres ran from o<) to !">. and of those above 22 inches, from 15 to 24. The timber on tliese strips, ninning about IDjiDii tVet M n acre, will yield approximately 5 cords of stumpwood an acre. DISTILLATION OF STUMPWOOD. Munger (6) states that 42 per cent of all butt logs in Oregon are fire scarred, and that 25 per cent of them are "pitched." The average diameter of the " pitchy " area on the basal cross section of the log is 14.7 inches on a tally of 1,184 butt logs. This means that 25 per cent of the stumps would also be " pitched " as the result of fire alone (p. 8). TABLE 5. Cruises on the Whitman National Forest, 1912-1916. Number of stumps per acre. Volume. Location. Area. Total Vol- ume per acre. 24-inch. 28.5- inch. 33.5- inch. 37-inch. Per acre. Ter area. Acres. Bd.ft. Bd.ft. Cords. Cords. T10S, R34E,sec.l9. .. 640 8, 511, 000 13, 299 26.59 13.29 8.86 6.649 6.649 4,255 T10S, R34E,sec.33. .. 640 6, 220, 000 9,718 19.43 9.72 6.48 4.859 4.859 3,109 T10S, R34E,sec.34. .. 640 7, 440, 000 11,006 22.00 11.00 7.34 5.503 5.503 3.521 T11S, R34E,sec. 1.. .. 640 5, 128, 000 8,012 16.02 8.01 5.34 4.006 4.006 2,564 T11S, R34E, sec. 2.. .. 640 5, 716, 000 8,931 17.86 8.93 5.95 4.465 4.465 2,857 T11S, R34E,sec. 11. .. 640 6,992.000 10, 925 21.85 10.92 7.28 5.462 5.462 3,495 T11S, R23E,sec.23. .. 640 6, 260, 000 9,781 19.56 9.78 6.52 4.890 4.890 3,130 T12S, R34E, sec. 3.. .. 640 5,900,000 9,287 18.57 9.28 6.19 4.643 4.643 2,971 T12S, R34E, sec. 10. .. 640 4, 776, 000 7,448 14.89 7.44 4.96 3.724 3.724 2,383 T 12S, R 34E, sec. 21 ... 640 3, 153, 000 4,926 9.85 4.92 3.28 2.463 2.463 1,576 T 12S, R 34E, sec. 28. . . 640 8,110,000 12, 672 25.36 12.68 8.45 6.336 6.336 4,056 Total 7,040 67,701 000 33, 916 Average 9,474 18. 95 9.47 6.32 4.737 4. 737 Stand on 56 forties 2,240 30, 821, 000 13, 759 27.52 13.76 9.17 6.879 6.879 15,409 Stand on 27 sections 17,280 153, 565, 000 8,886 17.77 8.88 5.92 4.443 4.443 76, 775 The total stand of western yellow pine for Washington is 12,500,- 000,000 feet in private and State ownership, and 4,500,000,000 feet in Government ownership, or a total of 17,000,000,000 board feet. Allowing a stand of 5,000 feet an acre, which is thought to be low, since Oregon and Washington are similar, the Washington area will be approximately 3,400,000 acres. The area of the yellow-pine land in the two States is approxi- mately 13,400,000 acres, carrying a commercial stand of from 5,000 to 7,000 feet an acre, or the equivalent of from 10 to 14 trees 24 inches on the stump, which will yield from 2 to 6| cords of yellow-pine stumpwood an acre. IDAHO, MONTANA, AND UTAH. Idaho. Montana. Utah. Total area acres 10 000 000 3 500 GOO (i) Total stand.. board feet 5S 050 000 000 14 OOO'OOO'OOO m Volume per acre do 5 800 4 000 4 000 Total annual cut (1917) do 315 009 000 150 905 000 4 676 000 Total area annually cleared (1917) Total annual volume of stumpwood . . . acres.. cords.. 54', 311 157,504 ' 37^726 75, 452 1,169 2,338 i No reliable figures obtainable. Many large areas of yellow-pine timber in Idaho are as good as the best of that in California and Oregon, but as a whole the stand 8 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. will probably average close to 6,000 feet an acre. Conservative estimates for the area would be 10,000,000 acres, and for the total stand, 50,000,000,000 feet. There is much wastage in butt logs, due to " pitchiness " resulting from fire scars and natural causes. Fires tend to make the stumps more resinous and to increase the number of those sufficiently " fat " to serve for purposes of distillation. It has been the experience of an Idaho lumber company that some of these " pitchy " butts occur in all the western yellow-pine timber. They state that these pitchy butts are more prevalent in the northern section of Idaho, but that this territory and the Baker, Oregon (Blue Mountain), territory pro- /.O ./ .2 .3 4 .J .6 .7.3.3 20J.2J4-.J.0 .7.3 .3 &?./.'.(? .4 .30 .7.0' WM. /* ' /VtfS -2.3 4- .J~.0 7.8 .& to./ ?.3 4- tf.C 7.8.9 Z'Corfs FIG. 2. Yellow-pine stumpage in 6 western States. A, volume of tree (thousand board feet) ; B, volume of stumpage (cords) ; C, difference between diameter breast high and diameter stump high (inches). duce less " pitchy " lumber than any other yellow-pine section that has come under their observation. From this it would seem that the question of " pitchy " butts is important, and should not be ignored by those who attempt to de- termine the amount of resinous wood to be obtained from any lo- cality. Since 25 per cent of the butt logs from the Blue Mountain region bear more or less pitch, and a wastage in " pitchy " butts trimmed off of from 4 to 5 cords a day is reported by one company, this constitutes a very important source of valuable wood for dis- tillation purposes. Samples sent to the University of Idaho com- pared favorably with the best stumpwood in yield of products. The DISTILLATION OF STUMPWOOD. 9 mill which submitted the samples was compelled to sell more than a million board feet of yellow-pine lumber at a loss, because of the amount of " pitchy " lumber in the butt logs. Inspection by one of the writers showed a large amount of this wood to be suitable for distil- lation. TABLE 6. Average volume of loestern yellow pine and reduction factors for various volumes and diameters of trees and stumps (Idaho and Montana). Diameter. Average volume. Reduc- Reduc- for different Breast high. breast height to stump height. Stump high.i Of tree. Of stump. volumes and diame- ters. Inches. Inches. Inches. Bd.ft. Cords. 22 2.0 24.0 500 0.25 1.0 23 2.0 25.0 550 24 2.0 26.0 600 25 2.0 27.0 675 26 2.0 28.0 750 0.375 1.5 27 2.0 29.0 850 28 2.0 30.0 ,000 0.50 2.0 29 2.5 31.5 ,150 30 2.5 32.5 ,250 0.625 2.5 31 2.5 33.5 375 32 2.5 34.5 ^500 0.75 3.0 33 2.5 35.5 .625 34 3.0 37.5 1,750 0.875 3.5 35 3.0 38.5 1,875 36 3.0 39.0 2,000 1.00 4.0. 37 3.0 40.0 2,250 1.125 4.5 38 3.0 41.0 2,400 38.5 3.5 42.0 2.500 1.25 5.0 39 3.5 42.5 2,600 40 3.5 43.5 2,700 40.5 3.5 44.0 2 850 42 3.5 45.5 3,000 1.50 6.0 1 See also Figure 2. TABLE 7. Cruise of 160 acres of western yellow pine in Boise County, Idaho (all trees calipered). Average diame- ter. Num- ber Ptumpwood. Num- stumps Aver- ber per acre Eauiv- age 24-inch equiva- alent Location. stand stumps lent, used in per acre. Breast high. Stump high.i per acre eauiva- lent. based on aver- age Per acre. Per section. reduc- tion. diame- ter. Bd.ft. Inches. Inches. Cords. Cords. Bd.ft. T 6N, R 5E. sec. 8 NW NW 14 693 25 5 27 5 29 38 20 55 7 34 293 6 715 T 7N. R 4E, sec. 35 SE NE . . . 15,144 27.4 29.4 30.29 16.83 7.' 57 302.8 900 T 7N, R 4E, sec. 35 NE NE. 13,866 25.5 27.5 27 73 19 40 6 93 277 2 715 T 7N, R 4E, sec. 35 NE SE . 15 783 26.7 28 7 31 57 18 70 7 89 315 6 800 Average, 4 forties 14,896 26.27 28.27 29.74 19.12 7.681 2189.2 782.5 1 From Table 6. 2 Total number of cords of stumpwood for entire area. 10 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. TABLE 8. Cruises of 478.85 acres of western yellow pine in Latah County, Idalw. Average diame- ter. Num- ber Stumpwood. Num- stumps Aver- age ber 21-inch per acre equiva- Equiv- alent Location. stand stumps lent, used in per acre. Breast high. Stump high.i per acre equiva- Fent. based on aver- age Per acre. Per area. red uc- tion. diame- ter. Bd.ft. Inches. Inches. Cords. Cords. Bd.ft. T 39N R 1W sec 2 lot 7 R 7.10 29 31.5 17.50 7.60 4.18 162. 39 1,150 T39N, R lW,scc. 9 SE NW 10,625 34 37.5 21.25 6.07 5.12 204.80 1,750 T39N. R IW.sec. 23 NE SW... ' 8750 34 37. 5 17.50 5.00 4.19 167.60 1,750 T 40N R IW.sec. 23 NE SW i 7500 28 30-0 13.00 7.50 3.75 150.00 1,000 T40N, R IW.soc. 24NENE... .10,500 26 28.0 21.00 14.00 5.25 210.00 750 T40N, R IW.sec. 24 NESE.. 8925 26 28.0 17.86 11.89 4.46 17v in 750 T40N,R2W,sec. 14SENW.... n.x7:> 28.0 23.75 15.83 5.93 237.20 750 T 42N R 3W sec 36 NE NW 17 500 29 31.5 35.00 15.30 8.75 350.00 ,150 T 41N, R 4W,sec. 29 SE SE... 9,625 34 37. 5 19.25 5.50 4.81 192.40 ,750 T 41N, R 4W, sec. 31 SE NW 10.000 32 34. 5 20.00 6.67 5.00 200.00 ,500 T 42N, R 4W, sec. 33 SE N W . . . 11,500 30 32. 5 23.00 9.20 5.57 222.80 .-'.-(> T 42N, R 5W, sec. 36 SW SE .. 11,000 29. 5 32. 22.00 9.17 5.50 220.00 ,200 Average, per forty 10,545 29.8 32.38 21.09 9.48 5.21 207.97 1,229 1 From Table 6. TABLE 9. Recapitulation of cruixes. Location. Area cruised. Total stand- Volume per acre. Number 24-inch trees per acre equiva- lent. Stumpwood. Per acre. Per area. T 39N, R 1W, B M... Acres. 4,840 10,291 7,380 4,733 6,147 4,240 Bd.ft. 24.967,000 52,218,000 69, 125, 000 36, 894, 000 37, 525, 000 25,680,000 Bd.ft. 5,158 5,074 9,366 7,729 6,098 6,056 10.32 10.15 18.73 15.46 12.21 12.06 Cards. 2.57 2.53 4.68 3.86 3.04 3.02 Cords. 12,438 26,136 34,538 18,423 18,686 12,804 T 40N, R 1W, B M T 40N, R 2W B M T 42N, R 3W.B M... T 41N, R 4W, B M T 42N, R 4W B M Total 37,671 246,409,000 123, 025 Average 6,580 13.15 3.28 1 The estimates include only yellow pine, which constituted but 53.34 per cent of the entire stand. A pure stand would be heavier. In all tables a slight discrepancy will be noticed between the total number of cords of stumpwood, when added and when computed. This is due to the dropping of decimals and the using of even numbers only in cruise tables. The average stand over large areas of yellow pine in Idaho is from 5,000 to 15,000 board feet an acre, or from 10 to 30 trees, '24 inches in diameter on the stump, the volume of stumpwood running from *2\ to 8 cords an acre. For more open stands the number of Mumps will be less, but such stumps are generally larger and consequently more resinous. Therefore the volume of " pitchy" wood will be consider- able, but can be determined only by a field survey of each region. DISTILLATION OF STUMPWOOD. 11 TABLE 10. Cruises of 3,200 acres of western yellow pine in Boise County, Idaho. 1 Location. Av- erage per acre for sec- tion. Average diam- eter. No. 24- inch stumps per acre equiv- alent. No. stumps per acre equiv- alent, based on av- erage diam- eter. Stump wood. Diam- eter equiv- alent, used in r^duc- tion. Breast high. Stump high. Per acre. Per sec- tion. T 7 N R 5 E, sec. 12 Bd.ft. 9,945 10,960 15, 336 18, 814 10, 453 Inches. 29.2 25.5 28.5 31.0 22.3 Inches. 31.7 27.5 30.5 35.5 25.3 19.90 21.92 30.66 37.63 20.90 8.50 15.10 14.60 13.68 18.66 Cords. 4.97 5.19 7.66 9.40 5.22 Cords. 3, 180. 8 3,321.6 4,902.4 6,016.0 3,340.8 Bd.ft. 1,170 715 1,050 1,375 560 T 7 N. R 4 E. see. 35 T 14 N R 5 E, sec. 30 T 14 N. R 3 E, sec. 12 T 13 N, R 5 E, sec. 7 Average 13, 101 27.3 29.7 26.20 14.11 6.51 220,761.2 974 1 Only yellow pine which is practically all over 22 inches diameter, breast high, or 24 inches diameter, stump high, is included. 2 Total number of cords of stumpwood for the entire area. TABLE 11. Recapitulation of cruises of 509,670 acres of pure western yellow pine. Location. Area. Diam- eter, stump high. No. trees. Av- erage diam- eter, stump high. Av- erage No. bd.ft. per tree. No. bd.ft. per acre. Av- erage no. 24- inch stumps per acre equiv- alent. No. stumps per acre of av- erage diam- eter. Av- erage no. cords stump- wood per acre. Total. Av- erage per acre. Kaibab National For- est Acres. 300,000 Inches. 13-16 18-22 24+ 3,258,000 2,400,000 2,220,000 11.76 8.00 6.74 Inches. 15.00 20.18 28.70 145 330 820 1,705 2,600 5,527 Total 11.05 6.74 4.0 8,148,000 298, 908 167,808 403, 788 25.50 9,838 South Payette River, Payette National Forest ___-!' _'- 52, 440 13-16 18-22 24 + 5.7 3.2 7.7 14.8 21.1 28.2 140 410 770 798 1,312 5,929 Total 11.86 7.50 3.62 870,504 16.6 8,039 Middle Fork, Payette National Forest Total 58,690 13-16 Ir22 24+ 297,558 190,742 434,306 5.07 3.25 7.40 15.38 20.50 29.50 165 355 900 786 1,154 6,660 = = -. -. 13.32 7.40 3.9 922,606 15.72 8,600 Weiser National For- est 98,540 13-16 18-22 24+ 451,367 274,926 675,984 4.68 2.79 6.86 14.29 20.04 29.00 120 325 850 562 907 5,831 ^^ Total 11.66 6.86 3.36 1,402,277 14.33 7,300 All commercial stands of yellow pine in Montana are confined to the western part of the State. Much of the timber is of about the same grade as that found in Idaho, but the stand usually is lighter and the timber a little shorter, and as a rule it contains a slightly smaller percentage of " pitchy " stumps. Many large areas in the 12 nr 1. 1. 1. TIX loon, r. s. DKPAKT.MKXT OF AGRICULTURE. State carry heavy stands of from 5,000 to 7,000 board feet, and in time the resinous wood may lv handled to commercial advantage. The working tables for Idaho can readily be applied in efforts to determine the volume of stumpwood on any area. The average stand to the acre for the entire commercial yellow-pine region of the State may be taken to be 4,000 board feet. The yellow-pine region of Utah is scattered over an extensive area, and until a more detailed survey is made it will be impossible to state the value of the stumpwood for distillation purposes. As a rule, it is far from transportation facilities and markets, so that for the present it may be considered as having but a slight bearing on the distillation problem. It has been assumed that the average stand from which the 1917 lumber cut was obtained carried 3,000 board feet an acre. In all probability it was decidedly higher, as the best stands are generally being cut first. This would reduce the number of acres a'nnually cleared, but would not affect the volume of stump- wood. COLORADO, SOUTH DAKOTA, AND WYOMING. Colorado. South Dakota. Wyoming. Total area J acres 916,415 707,000 8,000 Total stand > board feet 1 618 614 000 2 873,000 000 23 500 000 Volume per acre do.... 1,766 4,063 2,937 Total annual cut (1917) do 35,328 000 29,045,000 3 678 000 Total area annually cleared (1917) Total annual volume of stumpwood acres.. . t cords.. 20,004 17,664 7,149 14,522 1,252 1,839 i From Forest Service records. The commercial stands of yellow pine in Colorado are confined in a large measure to the national forests. They are scattered over nearly a million acres, but the volume to the acre is lower than that in any other State. It is not probable that any value may be derived from this stumpland in the way of distillation products. The chief yellow-pine area in South Dakota is located in the Black Hills region. The average stand for the 707,000 acres is 4,063 board feet an acre, making the volume of stumpwood about two cords an acre, which is thought to be low for distillation pur- poses, as the wood is not especially resinous. The stand in Wyoming is so small as to be entirely negligible for the purposes of distillation. SUMMARY. This brief survey shows that the quantity of stumpwood is enor- mous and that the problem of handling the cut-over areas is of first importance. It is known, however, that not all of these stumps arc sufficiently resinous for profitable distillation, under present conditions. DISTILLATION OF STUMPWOOD. 13 TABLE 12. Annual lumber cut of western yellow pine in the United States (9). Volume. State. 1914 1915 1916 19171 Stumpwood 2 California Bd.ft. 409 953 000 Bd.ft. 389 991 000 Bd.ft. 494 973 000 Bd.ft. 478 565 000 Cords. 239 282 Oregon ... 210. 438. 000 189, 203, 000 399, 102, 000 470, 488, 000 235,244 Washington 175. 426. 000 148,789 000 188 215,000 220,924 000 110 462 Idaho 159, 839, 000 201, 858, 000 240, 160, 000 315,009,000 157,504 Montana 134, 568, 000 118, 920, 000 138, 206, 000 150, 905, 000 75, 452 Arizona 78.667 000 75, 843, 000 92 133 000 78 147 022 39, 074 New Mexico 54, 728, 000 61,466,000 72,004,000 76, 149, 793 38,074 Colorado. . . 65,117,000 37, 241, 000 27, 848, 000 35, 328, 000 17,664 South Dakota 18,744 000 22 457 000 25 466 000 29 045 000 14, 522 All other 19, 885, 000 6,476,000 6,880,000 8,354,000 4,177 Total 1 327 366 000 1 252 244 000 1 684 987 000 1 862 914 815 931 455 1 From records of the district foresters. 2 For 1917 only. SUMMARY OF TABLE 12. Total volume, 1914-1917, inclusive (board feet). . 6, 127, 511, 815 Total area equivalent cleared, 1914-1917, inclusive, assuming 5,000 feet as average per acre .' (acres) . . 1, 225, 502 Total stumpwood, 1914-1917, inclusive , (cords) . . 3, 063, 755 If the areas are not agricultural in character, they should be allowed to reforest. In this case the land-clearing problem is not so important, although the stumps should be utilized, if it is economi- cally possible to do so. Table 12 shows that for the entire area of western yellow-pine land the average volume of stumpwood is 2.5 cords an acre, or 100 cords for every 40-acre tract. Probably half of this land carries double this amount of stumpwood. Be that as it may, it is certain that many thousands of cords of stumpwood must be removed before those who desire to make homes on the splendid yellow-pine lands, some of which are known to be among the best remaining lands obtainable for agriculture, can bring them into the proper state of cultivation and production. PURPOSE OF INVESTIGATION. In January, 1914, the Bureau of Chemistry, United States Depart- ment of Agriculture, in cooperation with the Department of For- estry of the University of Idaho, at Moscow, Idaho, began a study of the destructive distillation of logging and land-clearing waste in the State of Idaho, particularly of the yellow-pine stumps of that region. These investigations were instituted with the twofold pur- pose of ascertaining the feasibility of more effectively utilizing the timber resources of the Northwest and of reducing the net cost of clearing cut-over lands for agricultural purposes by the recovery of commercially valuable products from the stumps. The work resolved itself into determining (a) the nature, amount, and probable value of certain by-products obtained in clearing the land of stumps by 14 BTLLKTIX 1003, U. S. DEPARTMENT OP A< iIM( TLTURE. burning and the practicability of recovering these products by this method, and (b) the yield and value of products obtainable from yellow-pine stumpwood throughout the State when subjected to re- tort distillation. The chief aim of the cooperative work was to determine the value for distillation purposes of western yellow-pine stumps and such other logging or land-clearing waste in the State of Icttiho as might lend itself to the treatment. The abundance of yellow-pine waste is readily inferred from the volume of such lumber sent to market from mills throughout the State, and the relative abundance of yel- low-pine stumps in any section can be ascertained from timber-cruise records, supplemented by the proper volume tables. The quality of the stumps with respect to their resin content, on which depends their value for distillation purposes, however, can not be determined from such field or timber-cruise data. The results of careful field inspections have led to the conclusion that much of the western yel- low pine is of the relatively nonresinous or "bull pine" variety. Even the more resinous yellow-pine stumps varied so widely in their resin content that it soon became apparent that field investigations were indispensable to a proper knowledge of the proportion in which the various grades of stumps occur in the regions from which samples were collected. A knowledge of the conditions in the yellow-pine belt of the Atlantic and Gulf States made this all the more impera- tive, for the reason that the apparent preponderance of the lower grade of stumps clearly indicated that the profitable utilization by distillation of all yellow-pine stumps would be found impracticable, and that success in utilizing any of them would depend on a proper selection of material to be treated. From an agricultural standpoint the object of the work was to determine the practicability of reducing cut-over land clearing costs through recovery of by-products from the stumps. The extent to which distillation products from the stumps can be made to defray the cost of clearing such land obviously depends, among other things, on the total number of stumps to the acre, the number of these stumps suited to distillation purposes, the yield and value of the by-products, and, finally, the cost of recovering these by-products from the stumps to be treated. The first of these probably can be fairly well estab- lished from timber-cruise records for regions in which such data are available; the second is a combined field and laboratory problem; the third a laboratory and trade inquiry problem ; and the fourth a field and chemical engineering problem. The work accordingly resolved itself into an investigation involving each of these closely related problems. DISTILLATION OF STUMPWOOD. 15 TAKING SAMPLES. In the spring of 1914, samples, with the attendant field data, were obtained from four acres in different parts of the State typical of the regions they were selected to represent, namely: (a) Cut-over land of a lumber company in Latah County, hereafter referred to as the Potlatch-Deary region; (l>) the Coeur d'Alene and Hay den Lake region; (c) the South Idaho or Boise-Payette region; and (d) the Craig Mountain or Winchester region. In these field-sampling operations a rapid reconnaissance trip was made to get a general idea as to the abundance and apparent quality of the stumps in a region. On the basis of such knowledge an area considered representative of the district was selected, from which samples representing the different qualities of stumps, together with data for an estimate of their relative abundance and number per acre, w r ere taken. In the beginning the stumps were arbitrarily classed as " rich " when the top showed a marked resinous exudation, or, if burned over, revealed decidedly resinous wood when cut into with an axe, as "medium" when it showed but little of such exudation, and as "poor" when, although apparently sound, it was devoid of any resinous exudation. All stumps containing little if any resinous wood are classed as " bull pine," despite the fact that this term is usually limited to the western yellow pine less than 24 inches across the stump. Selected stumps of each class were removed by blasting, and only enough of their heartwood was taken to make, with wood from other stumps of the same quality, a cord sample of that class. This cord, or a smaller sample selected from this measured cord, was then shipped to Moscow for the experimental work. In all cases the sapwood was split off and rejected; hence the re- sults obtained in this investigation do not show what can be ob- tained from the whole stump of each quality, but only from the resinous heartwood. Because the western yellow-pine stumps ordi- narily contained so little heartwood (on an average about 50 per cent), stumps under 24 inches were considered only when they con- tained larger proportions of the resinous heartwood. Such stumps, in later years, should the sapwood rot off while the heartwood re- mained sound and resinous, would then be practically 100 per cent resinous, but, of course, would yield a much smaller quantity of total wood. Distinction between " yellow pine " and " bull pine" The term " yellow pine " is here used to designate such members of the Pinus ponderosa group as contain an appreciable portion of relatively resin- 16 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. ous, dark-colored heartwood, compared to the sap wood layer. " Bull pine," although often large, has relatively no such high proportion of the richer resinous heartwood. Botanically, the "bull pine' 1 is considered to belong also to the Pinus ponderosa, or western yellow- pine group, appearing to differ from the "yellow pine" only in being a less mature or more rapidly developed tree. Whatever may be the cause, the important fact remains that " bull-pine " stumps, aside from their content of what appears to be sapwood, are all but devoid of resinous matter and are utterly worthless for the recovery of turpentine or other distillation products (Table 14). " Bull-pine " stumps, irrespective of their size, therefore, are not included in the number of yellow-pine stumps to the acre in a given area or section, which makes it highly important to remember that no such distinc- tion between these classes of stumpage is made by timber cruisers. POTLATCH-DEARY REGION. The southwest quarter of the southeast quarter of section 15, town- ship 40 north, range 2 west, readily accessible and fairly represen- tative of the number, size, and quality of stumps to the acre of yellow-pine land in the Potlatch- Deary section of the State, had had a yellow-pine stand of 395,000 board feet a " forty," averaging 500 feet a tree. The average yellow-pine stand for the township was 234,000 board feet to 40 acres. The stumps were taken from a south slope, a ridge, and its adjacent lowland. The trees had been felled six or seven years before, and the stumps were generally found with all the bark. A few burnt- over stumps, of which the bark and sapwood had been destroyed, from trees said to have been dead when cut and in some cases felled for fuel wood 13 years earlier, were included. Ten stumps of each class were blown out and enough of the heartwood from each stump taken to make up a cord sample of each class. The stumps were re- moved by blasting with both 40 per cent and 20 per cent dynamite. Few of the stumps were removed entirely by the blast, most of them being either split through the middle, with only part of the stump thrown out, or left standing in a shattered condition. It was neces- sary, therefore, to employ a team of horses to remove enough of such shattered stumps to obtain a sufficient portion of each for the samples. All of the heartwood of the first few stumps shot out was removed and split to approximately cordwood size, and a sample taken from each stump thus entirely reduced. The labor cost, estimated at from $4 to $5 a cord, made it so expensive, however, that only a portion of each stump sufficient to obtain enough for a sample was reduced. The diameters of the ten " rich " stumps varied from 24 to 40 inches, with an average of 32 inches: those of "medium" quality, from 26 to 36 inches, with an average of 30 inches; and the "poor" stumps, DISTILLATION OF STUMPWOOD. 17 from 24 to 36 inches with an average of 28 inches. The cost of shooting the 30 stumps was as follows (spring, 1914) : Two men, 2^ days, at $2.50 a day of 10 hours $12. 50 50 pounds of 20 per cent dynamite 7.50 165 pounds of 40 per cent dynamite 28. 05 Fuses and caps 2. 75 Total 50. 80 Splitting the 30 stumps so as to obtain from each a sufficient por- tion for the sample required the work of 3 men for 3 days, which, at $2.50 a 10-hour day, amounted to $22.50. The cost of gathering and hauling the 3 cords of wood, requiring the services of 2 men and a 2-horse team for three-fourths of a day at $7.50 a day, was $5.62. If special stumping powder, selling for $12.50 a 100 pounds at that time, had been used, the powder cost could perhaps have been reduced by 20 per cent, or to $30 for the 30 stumps. The labor cost of plac- ing the shot holes and shooting the stumps could probably be reduced on a steady job. Against this it should be said that to have removed all the stumps completely would have required the time of a man and a team of horses for an additional day, as well as extra powder, fuses, and caps. The labor cost of shooting the 30 stumps should accordingly be left at $12.50. To have split the stumps completely so as to recover all the heartwood and permit the handling of the pieces by 2 men would have taken the 3 men 3 days more, making the cost of splitting the 30 stumps $45. On a steady job with men accustomed to the work, provided with tools or equipment that experience would suggest, this item possibly could be reduced by at least 50 per cent, or, in this case, to $22.50. On the basis of an average of 50 per cent heartwood in the stumps, it is estimated that at least 3 stumps are required to make a cord of wood, or about 10 cords from the 30 stumps. To gather up, haul, and load this on the car would cost 10/3 times $5.62, or $18.73. Summing up on this basis, the cost of these 10 cords of wood loaded on the car after a 1-mile haul is : Powder, fuse, and caps $30. 00 Shooting 12. 50 Splitting 22. 50 Gathering and hauling 18. 73 Total 83. 73 Cost u cord . 8. 37 Liberal allowances have been made in the items on which the cost of this yellow-pine stumpwood depends, and the cost a cord is con- fidently believed to be a minimum one. A material reduction of this figure need be expected only from the use of hitherto undeveloped 60953 21 2 18 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. land-clearing methods, from a failure on the part of the farmer to charge the value of his time and equipment in shooting, reducing, and hauling the stumps against the cost of the wood so delivered, or from a decided reduction in the selling price of explosives or in labor. The conclusions based on this method of sampling were subse- quently checked by removing all the yellow-pine stumps on a typical acre, taken to represent a good stand of large yellow pine in the Potlatch- Deary yellow-pine region, in the southwest quarter of the southeast quarter of section 36, township 42 north, range 5 west. The yellow-pine stand on this " forty " was 540,000 board feet, of which 240,000 board feet were from trees averaging TOO feet a tree, and 300,000 board feet from trees averaging 2,500 feet a tree. This figures out to a stand of 9 of the smaller trees containing a total of 6,000 feet and 3 large trees containing a total of 7,500 feet, or a total of 13,500 feet an acre. Of the 12 yellow-pine stumps on this chosen acre, 9 averaged 30 inches and 3 averaged 45 inches in di- ameter. The proportion and quality of the heartwood were so markedly different in the large stumps, as compared with that in the small stumps, that the woods from the large and small stumps were collected separately as two samples, and are hereafter referred to as " large " and " small " yellow-pine stumps, Potlatch, Idaho. A sample taken from so-called " rich butts," " tops," etc., was collected throughout the area from which the stumps at Deary were obtained, where a large amount of this material is available in the form of dead standing trees and windfalls. Judged by its appear- ance, little, if any, of it is rich in resinous matter. Hence one sample only, designated in the tables as " dead, down wood," was selected from the richer material of this class. COEUR D'ALENE AND HAYDEN LAKE REGION. The Coeur d'Alene and Hayden Lake region, taken as being rep- resentative of cut-over yellow-pine lands in northern Idaho, proved to be an unwise selection, as a larger proportion of " bull pine " or nonresinous material was found there than in the Pend d'Oreille River country farther to the north. It should be considered typical rather of the yellow pine in the territory within a 50-mile radius of Spokane. Two yellow-pine samples were taken, one on a ranch some 2 miles northwest of Hayden Lake towards Garwood, the other from the Mica Bay section of Coeur d'Alene Lake. The first was repre- sentative of the average quality of yellow-pine stumps proper in the Hayden Lake region, few, if any, of which showed resinous exuda- tion, and approximated 20 to 35 an acre in the closest yellow-pine stand of this region, which had been cut over a few years before. DISTILLATION OF STUMP WOOD. 19 The sample collected at Coeur d'Alene Lake was from " rich " stumps on a 20 to 30 acre tract near Mica Bay, not yet brought under culti- vation. Stumps of the quality represented by the sample do not occur in commercial quantities in the Coeur d'Alene Lake region. SOUTH IDAHO REGION. The wooded country throughout the South Idaho region is prac- tically undeveloped and without railroads. The forests remain un- touched, except in a few places where small-scale logging operations have been carried on to supply local mills. The timber resources are now being opened up for extensive logging operations to supply a mill of about 200,000 feet daily capacity at Barber, some 6 miles out from Boise. Working out from this company's logging camp, about 35 miles northeast of Boise, a hasty survey was made of an area which had been cut over in places 7 or 8 years before the company had taken over the land or timber rights. Although the timber throughout this region is largely yellow pine, few of the stumps appeared pitchy enough to be considered " rich." Fully 50 per cent were unsound and therefore worthless for distillation purposes. The stand of yel- low-pine trees or stumps 24 inches or more in diameter is estimated as not exceeding an average of 10 an acre. The actual count for several 1-acre plots, taken to represent a close stand, was 20, 22, and 18 trees, respectively. Three 1-acre plots taken to represent a stand of medium density ran 10, 6, and 9 trees an acre. Toward the other extreme the stand diminished to where, on the higher ridges, no yel- low pine was encountered. According to one of the company's cruisers, the whole of the Boise- Payette pine belt is very much like the land traversed, and an esti- mate of 10 yellow-pine trees, over 24 inches in diameter, an acre is liberal. Of the total number of yellow-pine stumps on a given area in the old cuttings perhaps 1 out of 25, or not to exceed 5 per cent, may be considered as belonging to the " rich " or " pitchy " class, probably 40 to 50 per cent are of " medium " quality, and the remainder of a quality from which it was not considered worth while to take a sample. Four samples were taken: (a) One from old cuttings to represent the "rich." or "pitchy," stumps; (b) one of "medium" quality, from the old cuttings; (c) one from green stumps from which the tree had been felled within a month of the time the stumps were shot ; and (d) one of green " bull-pine " stumps. Samples c and d, included because they were the stumps and logs from freshly fallen trees, though containing no well-defined heartwood, had an abundant exudation of what appeared to be gum on the freshly cut 20 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. surface. There was a little dead, down wood, and, as the tops of freshly fallen trees did not appear to be essentially different from those seen elsewhere and were obtainable nearer Moscow, a sample of this wood was not taken. It was difficult to judge the relative quality of the green stumps other than by the proportion of heart- wood to sapwood, the apparent resin content of the heartwood being quite uniform. The proportion of truly resinous heartwood to sap- wood varies greatly, however, a matter of importance in considering the value of the stumps, owing to the dearth of resin in the sapwood. Probably 50 per cent of the green yellow-pine stumps are of the quality represented by sample, and the remainder of inferior quality, in so far as the proportion of heartwood to sapwood is concerned. It would be very difficult to remove these stumps unless they were taken out with the logging operations, because of the fact that the mountainous topography and limited rainfall preclude an extensive agricultural development in the wake of the logging operations. The surface of the land presents an irregular series of steep ridges be- tween which wind deep, narrow valleys, where spur tracks are laid for the logs which are skidded down the hillsides to be loaded on tracks, moved as fast as the logs are taken away. The stumps, therefore, become inaccessible as soon as the tracks are taken up. CRAIG MOUNTAIN REGION. The yellow pine of the Craig Mountain region is a practically pure stand over an area some 10 miles long by 5 miles wide on an elevated, fairly level plateau. Receding from this central area the timber opens abruptly on Mission Canyon and the prairie country toward the north and west, and less abruptly toward the east, while toward the south it soon becomes mixed with fir and tamarack in the Salmon River country. A lumber mill with a daily capacity of about 125,000 feet operates in Winchester, which is centrally lo- cated in this yellow-pine belt. Comparatively little of the timber had been cut. In the central pine area the stand of yellow pine varied from 400,000 to 800,000 board feet a "forty," with an average of approxi- mately 20 stumps over 30 inches in diameter an acre where the stand was closest. The mill men and cruisers consulted agreed that probably 25 per cent of the total stand throughout this region is "bull pine." Seven samples were taken from this region, as follows: (a) Green yellow-pine stumpwood from several stumps blown out of the roadbed in extending spur tracks for logging purposes; (b) medium to rich stumpwood from stumps blown out in highway construction; (c) medium to poor stumpwood from the same locality in which the medium to rich samples were obtained; (d) medium to DISTILLATION OF STUMPWOOD. 21 rich stumpwood shot on land that had been cut over 4 or 5 years before; (e) dead, down yellow-pine wood collected from the better quality of knots, limbs, and trunks of trees lying throughout the woods; (/) rich, dead tops from trees felled in logging operations, the tops of which were dead from advanced maturity, and dead standing trees that had died from the same cause; (g) the better quality of tops and limbs from freshly felled trees. In addition, certain other samples were included in the investigation. The sam- ple designated "rich stumpwood, Viola" was from western yellow- pine stumpwood, from a ranch located near Viola. These stumps, the last of those remaining scattered through the field, had been shot out with dynamite, and the best snaked to the house for fuel. It was from this lot, the weight a cord of which was estimated to be 3,500 pounds, that a sample was taken. Trees cut from these stumps were said to have been felled 35 or more years before. The wood was very resinous, and to all appearances the same as the better grades of pitch pine of North Carolina or other southern States. The sample 30-inch stump from Priest River, obtained from a single large yellow-pine stump sent in from Priest River, Idaho, was selected as representing the best of the rich, or pitchy, stumps in that region. It had been blown out with dynamite, and the whole stump, roots and body, split into several pieces by the blast, was weighed, split, and reduced to stove-wood size. It was then mixed by being thrown together in a heap and repiled five or six times, after which it was neatly stacked under a shed. Dimensions of the pile of wood thus stacked were 8x7x1.5 feet, equal to a volume of 84 cubic feet. The stump weighed 2,190 pounds, so that as piled o 1 9Q v" 1 28 this wood weighed -~r > or 3,330 pounds a cord, in round numbers. The tree cut from this stump had been felled about seven years, not long enough for the sapwood to have rotted away or become detached from the lightwood within. This sapwood con- tained absolutely no turpentine and impoverished the wood to that extent. It is estimated to have constituted 20 per cent of the total volume of wood in the stump. The samples identified in Table 14 as "dead, down limbs" and "fire-scarred butts, Viola" were from yellow pine taken near Viola. Both samples were very resinous for these classes of wood. There was not a sufficient quantity of either to determine closely the weight of a measured cord. Nevertheless, if these facts are borne in mind and these samples are considered with other samples of the same classes of wood, they furnish an indication of the products to be recovered from these materials, which are quite plentiful in some sections. In some regions as much as 20 per cent of the butt logs 22 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. are fire scarred. The values on these samples given in Table 14 are, therefore, only estimates. SUMMARY. Northern Idaho: Rich stninpwood, Priest River. PotlatHi I>e:iry Region: Rich stumpwood, Viola. I -. a. Published ly th- Royal Academy of Science* at Stockholm. DISTILLATION OF STUMPWOOD. 29 came so violent when a temperature of about 300 C. was reached that the distillation could practically be completed without further heat- ing, and in less time than the richer wood with continued heating. It was necessary, therefore, in distilling the " bull pine " to watch the oil-bath thermometer carefully in running up the temperature for destructive distillation and turn off the heater flame when this period was reached. The reaction progresses so rapidly that the dis- charge of gas and vapors may exceed the otherwise ample condenser capacity, and loss of distillate result from imperfect condensation. The difference in behavior is due to the fact that the richer wood con- tains a much greater ratio of rosin to " cellulose. The heat set free during decomposition of the wood substance is more than offset by that required to effect decomposition of the rosin in such wood, and additional heat must be supplied to insure the decomposition of rosin and the distillation of the products. The fact that in the destructive distillation of nonresinous woods enough heat above a certain temperature is developed to complete the distillation without the application of heat from outside sources, necessitates the installation of larger condensers in the distillation of nonresinous woods than are needed in the distillation of resinous woods. When the exothermal reaction begins, it proceeds so rapidly that the condensers, which in the earlier stages were large enough to condense all condensable material, can no longer do so, and a loss of valuable products occurs if the condensers are too small to meet all the requirements that may be placed upon them during the exother- mal period. YIELDS. The yields of crude products obtained in the retort distillation, and of the refined turpentine and pine oil for each sample, are given in Table 14. A summary of these tabulations, giving the average re- covery from the various grades of wood distilled, is given in Table 19. 30 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. l mer- table ucts. .S I eupuedjnj, 5: 8 ! -apaio pnooeg d turp from epruo puooes epruo isayj epruo puooeg epruo isiij .-4 00 CO 1 04 O t~ 00 00 ^ OCO 04 co 04 to 0 00 CO 3^ <-l 04 O 0 c4 O4 00 -H ^t* OS ^ O CO Ol ^< H ICQ^CO.H^^CJ.H r~ o -4 ~ - oo c t^ r o >oco co o -H ^ eo ec t~ to co oo >!< to < ^ os M< 04 ic to t>- * o d '-4 -4 co o eg co ^iC(N^(Nojoocot-oooos^-io4o r^ w t^ oo co co 06^'^ oi^weocooi-H'^nJcooi o4 oi n ol ro co' pU009g N: -;< to' co o<5 ic 04* to ^odo'icr-' t-: t: 06 ei co c4 1 " 1 ' t^o -H oo oo rn os CT> co co ic oo to o c o> r^ * os co c os .-i O4>ci-i ^os-od co o5 co ^ ui co '^c4 I1I A^X^vaviHmiV^asva! s x s ^ 5s ^ CO^TcO~of O4^f O4~ C^~of ^ ^O4~of O4~O4" 1 O4*" O4" O4*" O4*" of of O4 and : | 4f A a g a" it I S I I I I m-i.i:-! 1 I 1 J ! ;ii|l l Hi Hi S3! ,1 J| ,? ,? ,s iillli^f'i * *'i S-3l5S'3 8-3 8-3 8.2 I SS5 DISTILLATION OF STUMPWOOD. 31 CRUDE PRODUCTS OF RETORT DISTILLATION. CRUDE WOOD TURPENTINE. The crude wood turpentine is distilled from the wood during the first stage of the destructive distillation. During this first stage of distillation the turpentine passes over for the most part unchanged, as it probably exists in the wood tissue. The crude first turpentine, therefore, is nearly free from pyroligneous bodies. It is often light in color, and usually possesses an agreeable odor. It has a specific gravity of about 0.875 at 20 C., a refractive index of about 1.4768 at the same temperature, and an initial boiling point of about 164 C. The crude second turpentine necessarily contains more of the pyro- ligneous or heat-decomposition products and of the heavier pine oils, since the retort operator cuts the distillate at the first signs of de- composition of the wood, indicated by the appearance of noncon- densable gases, and collects the remainder of the turpentine as " sec- onds." The heat-decomposition products of the rosin and wood constituents consist of acids, alcohols, ketones, phenols, aldehydes, etc., the nature and quantity of which depend on the temperature and rate at which the turpentine stage of the distillation is conducted. This crude second turpentine is darker than the crude first, and its color is sharper and more suggestive of wood decomposition. It has a specific gravity of about 0.910 at 20 C., a refractive index of about 1.4850 at the same temperature, and an initial boiling point of about 130 C. (due to the presence of decomposition products). The difference between these two crude turpentines is well set forth in Table 15. TABLE 15. Products of dry distillation of crude turpentine at 760 mm. pressure. Temperature of distillation ( C.). First turpen- tine. Second turpen- tine. Below 170 Per cent. 9 3 Per cent. 7 5 Between 170 and 175. . 52 8 9 06 Between 175 and 180. . 16 18 05 Between 180 and 185. . 18 02 Residue 21 9 47 37 The details of refining the crude turpentine are discussed on page 56. LIGHT OIL. The crude light oil is brownish black, has a sharp, penetrating, empyreumatic odor, an average specific gravity of about 0.995, a refractive index of 1.514, each at 20 C., and an acid value of about 29. Its average viscosity at 25 C. is 2.58 Engler. The yield is about 4^ gallons a cord of rich wood. Distilled in the ordinary manner at atmospheric pressure, using a fractionating column, it has an uncertain initial boiling point, around 70 C., due to the pres- 32 BULLETIN KHia, r. s. I'KI'AKTMKXT OF AGRICULTURE. ence of water and other low-boiling constituents, which rises rapidly to 160 C. The complex nature of this material is indicated by its wide temperature range when subjected to distillation. Typical results are shown in Table 16. TAP.I.K Hi. - -IH.xtilliitinn data of ennifinsite entile lifilif dl. Material distilling between Amount. Material distilling between Amount. 55 and 120 C . Per cent. 3.5 230 and 350 C. . Per cent. 54.3 120 and 180 C 13 6 Watery layer 1.8 1 80 and 230 C... 21.1 Residue soft pitch 5.7 On subjecting the various samples of crude light oil to dry dis- tillation at atmospheric pressure, using a fractionating column, an average of 34.5 per cent was found to distil below 225 C. Of the total distillate an average of 1.8 per cent was aqueous. This aque- ous portion, as well as the lighter portions of the oily distillate, con- tains quantities of acetic acid, methyl alcohol, and acetone. The difficulty of their recovery in a state pure enough for quantitative estimation is such, however, that it is as yet possible only to esti- mate the quantities of these bodies present. On treating the distillate obtained below 225 C. with an excess of 20 per cent alkali solution, a marked contraction in volume of the oil and decided heating were observed. When the oil thus treated was steam distilled to exhaustion, 87 per cent (1.3 gallons a cord) of total distillate was recovered as a rather sharp-smelling, light- yellow oil having an uncertain initial boiling point of about 125 C. On dry distilling this steam-distilled oil, 60 per cent passed over below 175 C., and the remainder distilled up to 250 C. In its behavior on distillation it shows a close resemblance to rosin spirits. By treating the crude light oil with alkali and distilling with steam as in the refining of the crude turpentine, 10 per cent (0.4 gallon a cord) of the oil is recovered as refined rosin spirits dis- tilling at from 130 to 200 C. and 20 per cent as a pine-oil fraction distilling at from 175 to 275 C. The pine-oil fraction distilling at from 175 to 275 C. has a lemon-yellow color like refined pine oil, but an unpleasant, altogether different odor, and can not be con- sidered as pine oil, except perhaps in certain of its constituents. Fifty per cent of it distils below 200 C. The residue from this steam distillation of the crude light oil forms a heavy emulsion with the alkali present. On the addition of acid about 10 per cent of the original oil separates out as a heavy tar that settles to the bottom. The remaining oil has about the density of water, slowly floating to the top, is dark, and has a mild odor. Distilled in a vannim of from 10 to 20 mm., 80 to 85 per cent (3.2 to 3.4 gallons a cord) of the crude light oil is recovered as a DISTILLATION OF STUMP WOOD. 33 clear, brownish-red oil that darkens on standing and has a creosote odor. The residuum from this distillation is a hard pitch. Ke- peated rectification of this light oil has given a series of fractions ranging from 166 to 176. The fraction from 174 to 176 gives an oily bromin addition product. Apparently it adds hydrochloric acid gas to form needlelike crystals after standing a number of days, but all attempts to make a nitrosyl chlorid were fruitless. The yield of crude light oil, compared to that of heavy oil, is small. Since the light oil differs but little from the heavy oil, it probably will be found expedient to collect and market or work it up along with the heavy oil in the operation of a commercial plant. One application to which this crude oil may be put is as a vehicle for cheap paints and shingle stains, and other such pur- poses for which certain of the creosote oils are now used. HEAVY OIL. The properties of the heavy oil which results chiefly from the destructive distillation of rosin resemble strongly those of rosin oil. The crude oil also contains decomposition products of the wood tis- sue, to which extent it is like wood creosote and rosin oil. The crude heavy oil is slightly heavier than water (average density of 1.048 at 20 C.), is brownish black, and has a penetrating, creosote- like odor. The average viscosity at 25 C. is 11.9 Engler. Like the light oil, it is comparatively unknown and untried, and there- fore lacks a well-established market value. Heavy oil is one of the important products obtained in the dis- tillation of resinous woods. The yield is exceedingly variable, run- ning from about 75 gallons a measured cord of very rich stump- wood to as little as 16 gallons from dead, down wood. Making up a large proportion of the total volume of oil recovered, its disposal to the best advantage possible is essential to the profitable operation of a commercial plant where the process is similar to that employed in this investigation. Consequently, certain experiments, looking to the most probable means by which an enhancement in the value of the crude oil may be expected, were conducted. From the results of laboratory work it was found that in sepa- rating its low-boiling fraction by distilling at atmospheric pressure from a flask fitted with a Hempel column, distillation begins at an uncertain initial temperature of about 85 or 90 C., with an average recovery of 25 per cent (8.7 gallons a cord) below 225 C. This fraction is quite similar to the corresponding fraction obtained from the crude light oil. The crude heavy oil can be used with some success for flotation purposes. In other fields of industry it must be sold largely in com- petition with products commonly obtained from coal tars such as 60953 21 3 34 BULLETIN 1003, U. S. DEPARTMENT OF AGEICULTURE. are used in the manufacture of roofing cement and shingle stains, and as. a softener and binder in treating heavy cotton cloths with metallic resinates, for water and mildew proofing purposes. In Rus- sia a similar pine product is used extensively as a leather dressing for harnesses, boots, etc. Either by itself or mixed with tar it might be successfully employed in the preparation of cordage, tar soap, moth-proof paper bags, leather dressings, etc. Bacteriological tests have shown it to possess a phenol coefficient equal to one-half that of carbolic acid. Both the light and heavy crude oils, as well as some of the other products of this investigation, were examined to determine their adaptability to flotation purposes by the United States Bureau of Mines at Salt Lake City, Utah (page 54), and also by several mining companies operating in the western States. One company reported that while all the pine oils were generally satisfactory for zinc ores, the crude light oil and a partially refined pine oil were particularly good. Another stated that the results differed only slightly from those obtained with oil from the southeastern pines, this being one of the most effective oils for flotation purposes. Probably all would be good for copper ores if used in conjunction with kerosene sludge acid. PITCH. The average yields of pitch from all classes of wood are not widely different except those from dead, down wood, which are much smaller than those from richer woods. No tests, either physical or chemical, have been developed with which to compare the qualities of the different samples of resinous-wood pitch found in commerce, other than the presence or absence of foreign matter, and no specifications on the basis of which to make such comparisons have been estab- lished. For this reason, and because its most important application is for impregnating fibers in the manufacture of oakum and cordage, and for closing seams in the decks of vessels, when it is combined in various proportions with tar and turpentine to secure the consistency desired, a systematic examination of individual samples of this ma- terial has not been made. These differ so little, the only apparent distinction that could be drawn between samples being a slight varia- tion in their relative hardness, that a general description will suffice. The pitch is a black, brittle to slightly pliant solid, having a specific gravity of 1.144 to 1.148 and in hardness varying from that of common rosin, in the more brittle, to that holding a finger print and possessing slight tackiness in the softer samples at ordinary tem- peratures. So susceptible is it to temperature changes that samples which were found to be tough or pliant through the day Inviunc quite brittle during the night. Its melting point is consequently very in- definite. It behaves like a viscous fluid at 75 to 100 C,, is sirupy DISTILLATION OF STUMPWOOD. 35 at 100 to 125 C., and free flowing at about 125 to 150 C. It is practically devoid of taste or odor, and dissolves readily in turpen- tine, but only very sparingly in either cold or hot alcohol, differing in this respect from common or black rosin. Its acid value was found to be 2, extracted with alcohol, against 150 to 180 for black rosin. It differs from what is purchased under Government contracts for " North Carolina pitch " in being, on the whole, blacker, and some- what softer, and in having, therefore, a generally lower melting point. It is believed, however, that this will not detract from its value in the uses previously enumerated, but rather that its somewhat greater pliability may be found to be advantageous. CHARCOAL. The charcoal obtained in these experiments from western yellow pine, especially that from the richer or more resinous samples of wood, is very soft and friable It retains an appreciable amount of bituminous matter, due undoubtedly to incomplete distillation, which causes it to burn with a long, smoky flame. Its possible application is suggested in industries where powdered fuel is used, or in metallurgi- cal operations in which the crushing strength is not a prime requisite. The charcoal from " bull " pine was in every respect superior to that obtained from yellow pine proper, and, in general, the quality of the charcoal fell off as the rosin content of the wood increased. Compared to that from hardwood, the western yellow-pine char- coal must be considered of inferior quality, especially as to hardness. Tamarack charcoal has a much denser structure and is not so friable as that obtained from yellow pine. Moreover, it is clean or free from bituminous matter, and appears to be quite similar to hard- wood charcoal. ACID LIQUOR (PYROLIGNEOUS ACID). The specimen log of a run (page 27) shows that an aqueous dis- tillate which is nearly pure water comes over with the turpentine at the beginning of a distillation and is rejected. As the heating is continued, the wood tissue begins to decompose and the aqueous liquor takes on a straw color. From this point it contains acids and alcohol in varying quantities, and constitutes a true acid liquor, which in these experiments was retained and examined. The acid liquor results from chemical transformations of bodies making up the wood tissue and rosin contained in the wood, brought about by heating the wood to a sufficiently high temperature. This reaction is a true chemical process, none of the compounds found in the liquor occurring in the untreated wood. The action is alto- gether different, therefore, from the recovery of turpentine and pine oils, the separation of which is effected by a physical change of 36 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. state. In other words, the heat serves only to convert these oils into vapors, which, after being cooled in the condenser, are col- lected essentially as originally present in the wood. The three important constituents of acid liquor are acetic acid, methyl (wood) alcohol, and acetone. Up to the present time these products have been obtained almost exclusively from hardwood. Owing to the greater amount of tarry substances present, softwood acid liquor is extremely difficult to free from this constituent, and the calcium acetate made therefrom is inferior in quality to that from hardwood acid liquor. The yield, consisting of methyl alcohol and acetone, is also substantially lower than that from hardwoods. The proportions of acid, alcohol, and acetone as found in these western yellow-pine acid liquors (Table 17) were obtained by analyzing a composite sample of acid liquor from each set of charges run on the various kinds of wood. 6 TABLE 17. Composition of add liquor*. Grade and source. Acid liquor, per cord. Acetic acid. 80 per cent acetate of lime (calc. from acetic acid), per cord. Methyl alco- hol. Acetone. Dissolved oils and tars. Per liter. Per cord. Per liter. Per cord. Per liter. Per cord. Per liter. Per cord. Poor stump wood, Deary Rich stumpwood, Deary Medium stumpwood, Deary. . Dead, down wood, Deary Rich stumpwood, Coeur d'Alene Galls. 59.4 55.9 54.3 53.4 60.9 61.4 64.3 63.9 59.5 63.6 69.2 62.4 63.6 74.0 75.8 63.2 80.8 66.6 65.7 Gms. 67.76 64.67 67.82 64.49 64.37 65.44 77.55 64.67 68.12 71.05 70.40 73.41 65.12 41.95 48.35 57.90 49.67 58.21 59.72 Lbs. 33.6 30.2 30.7 28.7 32.7 33.5 41.6 34.5 33.8 37.7 40.7 38.2 34.6 25.9 30.6 30.5 33.5 32.4 32.7 Lbs. 55.3 49.7 50.5 47.2 53.8 55.1 68.5 56.8 55.6 62.0 67.0 62.9 56.9 42.6 50.4 50.2 55.1 53.3 53.8 Galls. 27.82 25.45 26.11 25.98 23.19 27.35 29.37 25.21 25.34 27.64 26.18 30.17 29.27 13.88 24.32 27.71 28.09 28.21 18.26 Goto. 2.10 1.80 1.79 1.76 1.79 2.13 2.40 2.04 1.91 2.23 2.29 2.38 2.36 1.30 2.34 2.22 2.S7 2.38 1.54 Gms. 2.24 2.77 2.44 2.33 2.00 1.92 2.21 2.12 2.16 2.42 2.26 1.81 2.07 1.49 1.75 2.09 1.73 2.10 1.69 Galk. 0.20 .16 .16 .15 .15 .15 .18 .17 .16 .19 .19 .14 .16 .14 .17 .16 .17 .17 .14 Gms. Lbs. 120.08 L84.68 156.86 122.34 136. 11 172. 12 133.90 128.54 161. 16 159.29 152.37 143.31 66.15 11'.'. 71 117. M 78, '.'s 114 I JO. 83 56.0 60.9 69.9 62.2 69.7 92.3 71.4 63.8 85.5 92.0 79.3 76.0 40.8 75.7 62.1 53.2 63.6 66.1 Medium stumpwood, Hayden Lake Bull-pine stumpwood, Boise.. Medium stumpwood, Boise... Rich stumpwood, Boise Green selected stumpwood, Boise Green selected stumpwood, Craig Mountain Rich cut-over stumpwood, Craig Mountain ... Rich ^cut-over stumpwood, roadside, Craig Mountain... Tamarack stumpwood, Mos- cow Mountain Selected dead, down wood, Craig Mountain Selected dead tops, Craig Mountain Selected green tops and limbs, Craig Mountain Medium stumpwood, road- side, Craig Mountain Rich stumpwood, near Pot- latch "Tin- analyses of tin- arid liquors w.-iv made by V. E. (Jrotlis. h :iml C. <'. Sponcer, I'.uivaii <>f riimiistry, I'nit.d States Department of DISTILLATION OF STUMPWOOD. 37 The yield of calcium acetate is approximately but one-fourth of that generally obtained in distilling the best hardwoods. Probably on a commercial scale the yields would be somewhat less than those shown by the analyses. The yield of wood alcohol also is but one- fourth of that generally obtained in hardwood distillation. PRODUCTS OBTAINED IN REFINING CRUDE TURPENTINE. REFINED TURPENTINE. In order to separate the valuable turpentine constituents of the crude turpentines from the pyroligneous and resinous heat-decompo- sition products of the wood, the crude turpentines are first treated with caustic soda, which combines with acids and resinifies the aldehydes and phenols, forming nonvolatile compounds. By a subsequent steam distillation the turpentine and pine oil are recovered. Just as in the case of the original retort distillation of the wood, the oily products of the steam distillation are separated into several fractions. The first product is called " first grade " or " first-quality refined turpen- tine." The receivers are changed at a certain point (page 58), and the distillate which then comes over is called " refined second- quality turpentine." This has distilling temperature limits somewhat higher than those accepted for true commercial wood turpentine. Finally, the receivers are changed again, the last of the distillate be- ing called " pine-oil fraction." On refining crude first turpentine a yield of approximately 80 per cent of refined first-grade turpentine is obtained, most of which dis- tils between 170 and 175 C. From crude second turpentine the yield of refined first-quality turpentine lies in the neighborhood of 43 per cent. The other distillates from the crude turpentines are as follows: From crude first turpentine, 5J per cent refined second- quality turpentine fraction and 7| per cent pine-oil fraction; from crude second turpentine, 13 per cent refined second turpentine and 12 per cent pine-oil fraction. 38 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. 1? 388 888 fl? hi SSS rHM^ ec00000>00 "50 O gggggSgggSg gggggggSS gg 8 ill d K J d -3 COOOQOQ GQWOOOQai ........... /- - i-5 LJ fliJ GjJ fljj fljj fljj d i j Average. Maximum. 1 Average. j Minimum. 5 Crude first turpentine (A) gallons.. Crude second turpentine (B) gallons.. Total do.... Crude light oil do.... Crude heavy oil do 17.1 17.8 13.3 7.6 14.9 11.1 12.1 10.5 6.8 6.4 9.0 8.1 9.9 7.4 8.7 5.0 9.3 6.2 17.8 13.5 4.5 2.8 8.6 6.3 34.9 8.3 70.5 74.4 13.3 7.9 21.0 2.7 29.5 55.9 ===== 10.0 3.1 26.0 ===== 4.6 46.0 64.4 == 11.8 5.0 22.6 4.9 31.7 74.4 ==: 9.7 6.1 13.5 17.1 2. 8 3. 6 24.4 26.5 54.31 64.1 5.1 7.1 1.5 3.6 16.1 3.2 32.1 69.2 === 8.1 3.8 14.9 ~2^5 30.1 63.6 ===== 7.2 2.5 15.5 " 2.9 31.1 66.4 - 7.6 3.2 31.3 4.9 47.0 75.8 13.6 2.9 7.3 2.8 19.5 53.4 " 14.9 3.6 28.6 63.6 6.4 1.8 13.7 5.9 2.9i 3.3 23.6 in. 1 59.4' 80.8 5.7 2.0 2.8 1.1 Acid liquor do Refined first turpentine from A gallons.. Refined, first turpentine from B. .. gallons Total do 21.2 ===== 1.3 13.4 == .6 16.8 - .8 15.8 g JU, 4 10.7 g 11.0 == 7 10.6 - 4 10.8 ~ 16. 5J 3.4 "T" 13 3 8.2 7 8.5 4 3.1 3 Refined second turpentine from A gallons.. Refined second turpentine from B gallons.. Total do.... Pine oil fraction from A gallons.. Pine oil fraction from B gallons.. Total do.... Merchantable turpentine gallons.. Merchantable pine oil 2.3 .9 1.5 1.5 .9 1.1 1.0 .5 .8 1.9| .3 .8 .7 .3 3.0 == 1.7 2.6 1.7 == .9 1.1 2.3 == 1.2 1.5 1.9 == 1.1 1.2 1.3 .3 .9 1.7 - " . .7 1.0 1.4 ===== .5 .5 1.2 .3 .4 1.3 ^ .4 3.2 -^- ' 1.6 2.8 .6 .3 .3 1.5 .7 1.1 1.1 .3 .6 .6 .2 .3 4.3 === 25.7 3.1 237 988 3,500 2.2 -'"" 16.2 1.6 110 670 2,500 2.7 19.8 2.0 188 789 2,812 2.1 18.0 1.6 188 800 3,000 1.2 ===== 8.9 1.0 102 651 2,200 1.7 12.7 1.3 131 711 2,417 .9 " 12.5 .s 144 823 2,500 .8 *_"" 11.8 .8 143 768 2,400 .9 .-._.^ 12.2 .8 143 795 2,450 4.4 21.0 3.1 104 863 3,000 .6 4.6 .4 42 671 2,000 1.8 10.2 1.3 84 790 2,400 .9 9.7 .8 83 714 2,100 .5 3.8 .4 22 764 2,400 Pitch pounds. . Charcoal do Cord weights do.... The average weight a cord of the rich stumpwood is 2,612 pounds, as against 2,450 pounds for selected stumpwood, and 2,412, 2,400, 2,100, and 2,400 pounds for medium stumpwood, dead, down knots and limbs, poor stumpwood, and green tops and limbs, respec- tively. The corresponding yields of refined first turpentine are 16.8, 10.8, 10.7, 8.2, 8.5, and 3.1 gallons a cord; and the yields of total merchantable turpentine are 19.8, 12.2, 12.7, 10.2, 9.7, and 3.8 gallons a cord, respectively. With the exception of that from the green tops :in.l limbs, the yield of turpentine a cord follows the weight a cord. The yields of pine oil and crude light oil, while not varying greatly, DISTILLATION OF STUMPWOOD. 43 show the same tendency to follow the weight a cord and field classi- fication of the wood. This tendency is shown also by the yield of heavy crude oil and of pitch. The acid liquor and charcoal, how- ever, are not subject to any such general deductions, although the highest yields of acid liquor are generally given by the green woods, followed by the richer stumpwood. In all probability this is due to the fact that acetic acid is one of the decomposition products of rosin. An experienced person can classify stumps in the field into several grades from which the average yields of valuable products differ to such an extent as to necessitate a proper selection of the material before collection. COMMERCIAL DISTILLATION PROCESSES. There are four general processes for the recovery of products from resinous wood. Two of these are destructive distillation processes and two are nondestructive extraction processes. They are : (a) The common or ordinary destructive distillation process; (b) the con- trolled temperature destructive process ; (c) the steam distillation or extraction process; and (d) the solvent extraction process. Of these the ordinary destructive distillation process is the only one which seems to be well adapted to the stump-disposal project in the North- west. ORDINARY DISTILLATION PROCESS. The wood-distilling oven now in general use for the destructive distillation of wood is an outgrowth of the old charcoal heap. By- product charcoal kilns, round iron retorts, and rectangular iron or concrete ovens are in use, the rectangular oven being preferred in the best practice. Experience with these different forms has taught that there is a mean temperature which gives the most satisfactory yields. This temperature is necessarily more difficult to maintain in direct-heated retorts, the smaller of which have the further dis- advantage that the charcoal must be removed by hand, necessitating a loss in time required for cooling as well as a fuel loss in reheating the retort for the next charge. The uneconomical working of the round retort has led to the de- velopment of the rectangular oven. Such ovens are of steel or con- crete construction and are heated either directly by fires under them, in the case of the steel ovens, or by means of internal-heating flues in the concrete ovens. The second method is said to be better adapted to softwood distillation. The height and width of the ovens are uniform, being in general 8 feet 4 inches and 6 feet 3 inches, re- spectively, and the length ranges from 26 to 54 feet or more, accord- 44 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. ing t<> the desired capacity. An oven 52 feet long, G feet 3 inches wide, and 8 feet 4 inches high holds 10 cords of wood. The charge of wood, of regular con 1 wood size, is loaded onto steel tramcurs of special construction and hauled into the retort or oven, which is, of course, tightly closed during the distillation. At the end of this operation, the train of cars bearing the still hot charcoal is hauled out into the cooling shed of sheet iron, where the charcoal cools down without loss of fire. Simultaneously, another trainload of wood enters the oven, and the new distillation proceeds with a minimum heat loss. In addition to the ovens, coolers, cars, and necessary brickwork or the setting of the ovens, condensers, which should be of ample ca- pacity to handle the distillate under the most unfavorable operating conditions, will be required, as well as stills, steel tanks to hold the product, wooden tanks, pumps, generators, steam boilers and engine, yard tracks, piping, etc., and the necessary buildings for housing the plant. A conservative estimate of the cost of such a plant is between $4,000 and $5,000 a cord capacity. Before the war these plants could be built for from $1,500 to $3,000 a cord capacity, or at a total cost, including working capital, of approximately $20,000 for a 10-cord .plant. The cost of construction and of operation and the design and character of the equipment "will vary, and quite widely, with the pro- posed location of the plant and the work it is to do, and with the experience and practice of the designing and constructing engineers. For these reasons, no details of equipment or specifications are given. This information can best be secured from wood-distillation engi- neers and from builders of the equipment, whose advertisements ap- pear in the various industrial journals. The Bureau of Chemistry can furnish a list of engineers and builders of wood-distilling plants. CONTROLLED TEMPERATURE PROCESS. The controlled temperature or circulating oil process and retort have been fully described in the preceding pages. Even on a com- mercial scale a prerequisite of this process is that the pieces of wood be relatively smaller in diameter than those used in the ordinary de- structive process, to insure rapid distillation. When properly car- ried out, better separation of the several products of distillation is obtained, with the result that the turpentine ordinarily obtained com- mands a slightly higher price (3 to 5 cents a gallon) for paint or varnish purposes than the turpentine produced by the regular de- strnctive process, in which the temperature is not definitely con- trolled. While tliis process yields a better grade of wood turpentine, the equipment and upkeep are more expensive, and greater skill and DISTILLATION OF STUMPWOOD. 45 a larger force are required in operating than for the uncontrolled process. For this reason it is rarely used for distilling resinous wood. STEAM DISTILLATION PROCESS. The steam distillation process requires that the wood to be ex- tracted shall be finely divided by chipping or shredding before treat- ment ; the finer the chips, the more rapid and complete the extraction. For this reason the steam process has been installed by several saw- mills for the recovery of turpentine from sawdust. The best results are not obtained with all dust, however, as it packs so tightly that the steam is kept from penetrating throughout the entire mass to be extracted. Chips of a size passing an inch and retained by a quarter- inch screen are desirable, and a limited amount of sawdust can be mixed with such chips. Few plants, other than lumber mills where the production of wood turpentine and pine oil is only a side issue, have continued to operate on the steam process alone, and have invariably closed when turpen- tine sold at less than 50 cents a gallon. The turpentine produced by this method is of high quality, approaching that made by the regular distillation from gum. The practicability of maintaining a steam distillation plant depends entirely on market conditions ; if the price of turpentine is sufficiently high the steam method will be a paying proposition. The steam distillation outfit is now usually installed in conjunction with a solvent plant that can extract the residual wood chips for the recovery of rosin and certain of the heavier pine oils. SOLVENT EXTRACTION PROCESS. In the solvent process also the wood must be finely divided. This process is one where the wood is extracted in large, tight digesters at a relatively high temperature by means of suitable volatile sol- vents, the choice of which is determined mainly by price. Gasoline, coal tar, naphtha, or turpentine can be used, gasoline being the one in common use. When the solvent is added in the beginning of the operation, that is, with no previous steam distillation, all of the solu- ble pine products are removed altogether, and the resulting mixture is fractionated to recover the naphtha or other solvent and to sepa- rate the turpentine and pine oils from the rosin. The rosin obtained in this way is not so free from tackiness as pure gum rosin, and has a rather darker color, but is quite clear when properly made. Fur- thermore, it is very difficult to remove the solvent completely from the turpentine. It has been found advantageous, therefore, to com- bine the steam and solvent processes, the only objection' to this being that the steam leaves the chips in a moist condition, in which state the extraction does not take place as readily as if they were abso- lutely dry. 46 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. BATH PROCESS. An advantage of the bath process, another method which has been used to a limited extent, is that the wood does not require previous shredding. The wood is run into the retort on cars, and the retort is flooded with a high-boiling material, 'such as molten rosin, pitch, or tar, heated to a sufficiently high temperature. Most of the ex- tracted turpentine and pine oils are volatilized at the temperature of the bath, and the rest is blown out of the bath with steam. The remaining wood, which is saturated with the rosin or other material of the bath, may be destructively distilled to recover the light and heavy crude oils, tar, charcoal, and pitch. FEASIBILITY OF DISTILLING WESTERN YELLOW PINE. Yellow-pine stumps of a quality such as to yield more than 12J gallons a cord, the average yield from medium-grade stumpwood, of merchantable wood turpentine, of the properties shown in Table 18, and other products in corresponding proportion, are compara- tively scarce. " Fat " or " pitchy " stumps, averaging 20 gallons of merchantable turpentine a cord, are not sufficiently numerous to be considered in a class by themselves as an impediment to land-clearing operations, and would need to be hauled for long distances in supply- ing wood to distilling plants. The daily yield from a 10-cord plant and the market value of the products from the rich portion of medium-grade stumps, based on the yields obtained in these experiments and on the prevailing eastern prices June, 1918, using the ordinary ovens in general use, would be approximately as follows: Merchantable turpentine 127 gallons @ $0. 50 $63. 50 Pine oil 13 do. @ .40 5.20 Light oil (at tar oil prices) 35 do. @ .20 7.00 Heavy oil (at tar prices) 275 do. (6 barrels) @ $0.15 41.25 Pitch 7 barrels ( 1,400 pounds ) @ $3.50_. 24.50 Charcoal 350 bushels (7,110 pounds) @ $0.12_ 42.00 183. 45 Total value of products a cord of selected medium-grade resinous wood or heartwood .$18. 36 The average yield and market value of the products recovered from a cord of rich stumpwood on the same basis are estimated to be : Merchantable turpentine 19.8 gallons @ $0.50 $9.90 Pine oil 2.0 do. @ .40 .80 Light oil 4.5 do. @ .20 .90 Heavy oil 46. do. @ 15 0. 90 Pitch . 138. pounds @ 3. 50 a barrel 2. 41 Charcoal 38. bushels (790.0 pounds) @ $0.12. 4.56 < Total value of products a cord 25. 47 DISTILLATION OF STUMPWOOD. 47, These yields and values are comparable to those obtained in dis- tilling longleaf-pine lightwood in the South Atlantic States, as shown by the following figures, taken from Bureau of Chemistry Bulle- tin 144 : Products from 1 cord (4,000 pounds) of longleaf yellow-pine lightwood (destruc- tive process). Total crude oil - gallons__ 36 to 120 Refined wood turpentine do 5 to 20 Pine oils do 2 to 5 Rosin oil do 20 to 65 Light and heavy oils : Creosote gallons 8 tQ 20 Rosin spirits do 2 to 10 Charcoal bushels__ 30 to 50 Cost of operating per day and per cord (1915 figures). 10 cords of wood, at $8.37 a cord, delivered $83. 70 Fuel wood, in addition to gases and fine charcoal, 10 cords, at $2.50 a cord, delivered 25. 00 Labor, 8 men (3 shifts), at $2.50 a day (average wage) 20. 00 Technically trained works manager, at $125 a month 4. 15 Depreciation, at 15 per cent of investment in plant ($20,000) 8. 20 Upkeep, at 8 per cent of investment in plant ($20,000) 4.40 Insurance, at 3 per cent of investment in plant ($20,000) (average) 1. 65 Chemicals for still house, etc 1. 00 Barrels or other containers for making deliveries 15. 00 Interest on total investment ($25,000), at 6 per cent 4. 11 167. 21 Total daily production cost, exclusive of sales or marketing ex- penses, a cord 16. 72 Marketing expenses, although an important item, are not included, because they depend largely on the business policy of the manage- ment and upon competition. The cost of operating a plant in the South Atlantic States is but little more than half this estimate, because of the much lower cost of wood and of labor in the South. If the medium-grade wood could be distilled at the usual southern cost, it would yield a fair return. The approximate cost of operating a destructive distil- lation plant in the South Atlantic States is as follows : Cost of wood for distilling, a cord $1. 50 to $3. 00 Management, labor, fuel, packing, a cord 2. 50 to 6. 00 Interest and depreciation, a cord . 60 to 1. 60 Total 4.60 to 10.60 The values assigned to the several products are representative of those prevailing on the eastern coast shortly after the European war started. To this must be added the cost of transportation to 48 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. the West and western dealers' profits, which were not included for the reason that they vary greatly, and also because local freight rates to interior points would, in many instances, be nearly as great from western points to consuming points as the through rates from the South to the same consuming points. Since, in any event, sin -h competitive freight charges would vary greatly with the locality, they are not included in the estimation of values here given, but they must receive very careful consideration before the erection of a plant for the recovery of products from wood. On the basis of the foregoing carefully considered and conserva- tive estimates of cost of production and of the value of products, it must be concluded that stumps of medium quality, giving the aver- age yields stated, can not be profitably utilized generally by the destructive distillation methods. Needless to state, if, because of exceptionally favorable local conditions, the cost of wood at the plant can be materially reduced, wood of medium richness could be profitably distilled. Such localities should be given very thoughtful and systematic consideration by experienced and practical distilla- tion experts before undertaking their exploitation. Since poor stumps and dead, down wood contain even less resin- ous matter than the medium stumps, they could not be profitably distilled. On the other hand, the rich or pitchy stumps contain enough resins to make their distillation profitable in those localities where they are sufficiently numerous. With wood containing enough resin- ous matter to average the yields given for rich stumpwood, obtain- able at even $10 a cord, a wide margin of profit is possible by the process outlined, provided all the products can be marketed at prices not materially lower than those used in the foregoing estimate. To maintain an adequate wood supply of this quality, sufficient for a plant to operate a number of years, it will be necessary to resort to a long-distance railroad haul and long-distance wagon transporta- tion to railroad sidings. For this reason, a cost of something like $10 a cord should be allowed in estimates for such wood, the cost of getting out the stumps alone exceeding $6. The possibility of ob- taining at reasonable prices sufficient quantities of rich stumps which are thinly distributed over the land, entailing a high cost of collect- ing, is the vital point in considering the practicability of wood dis- tillation in the Pacific Northwest. The impression that more material than that obtained from the rich stumps might be drawn on, because, the margin of profit for this material appearing quite large, an appreciable proportion of wood intermediate in quality between that from rich and that from medium-grade stumps combined with the rich grade would give a material worth working up. would in general be misleading. DISTILLATION OF STUMPWOOD. 49 When stumps of the different grades (p. 15) were dynamited but little difference was found between the poor and medium-quality stumps. Furthermore, unless the exudation of rosin is exception- ally abundant, it can not be taken as an indication that the stumps are rich or pitchy. So disappointing was this superficial indication of quality, used before its true value was established from dyna- miting a number of stumps, that, to avoid shipping a lot of what was plainly worthless material, the poor stumps were taken from those that had been classified as medium, leaving only a few spe- cially selected stumps from which the rich wood proper was ob- tained. In view of these facts, poor and medium-quality stumps, as the terms are used in this bulletin, are those in which the sound heart- wood approximately equals in resinous .appearance that found in the heartwood of an average yellow-pine log, except that it is richer toward the spreading of the roots. The resinous material in such wood comes largely from this portion of the stump. Medium stumps differ from poor stumps only in that there is a somewhat larger proportion of the very resinous wood at the spreading of the roots, the main volume of heartwood in these two classes of stumps appearing to be essentially alike. Rich or pitchy stumps differ from the medium in that the heartwood is more uniformly resinous throughout the whole of the stump and constitutes perhaps from 60 to 80 per cent, or more, of the whole stump, while in the poor and medium stumps the resinous portion constitutes less than half of the entire stump. To verify the conclusion that the rich or pitchy stumps average not more than a cord an acre of wood suitable for distillation, all the stumps on a typical area were removed, representative samples selected, and an estimate made of the total quantity of such wood on the area from which stumps were taken. This selected represen- tative acre contained 12 stumps, 9 of which were classed as medium to poor, and 3 as resinous or rich. The 9 nonresinous stumps con- tained between 3 and 4 cords of wood, of which but 1,500 pounds, or one-half cord, was sound heartwood, the remainder being doaty, nonresinous sapwood, which was separated from the heartwood in the field, only the heartwood being taken to the laboratory. At least 80 per cent of worthless nonresinous material was split out of these stumps in obtaining the half cord of heartwood. In the large resinous stumps there were 1J cords of resinous wood, all of the quality represented by the sample. The nonresinous stumps, though quite large (36 to 40 inches), were smaller than the resinous stumps. 60953 21 4 50 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. The wood selected from that classed as the less resinous stumps was richer than that from the 3 rich stumps. Weight for weight of material in the selected samples this is true. However, of the wood running 18 gallons of turpentine a 3,000-pound cord, only about 1,500 pounds, or one-half cord, in the entire lot of 9 stumps contained an estimated volume of 3 or 4 cords of w r ood. To run all of this wood would eliminate the cost of splitting out the resinous wood from the sapwood. It would, however, quadruple the cost of rail and wagon haul and the time and cost of distilling, and, at the same time, would cut down the yield to about 5 gallons a cord of very inferior turpentine, with a proportional reduction in other products. The half cord of resinous wood from the 9 stumps, combined with that from the 3 more resinous stumps, gave about 2 cords of wood, running 17 gallons of turpentine a cord. Had all the wood on the acre plot been used, there would have been 6 cords, yielding not more than 6 or 7 gallons of turpentine a cord, with the other prod- ucts in like proportions. Neither the results of these experiments nor the wood-distillation practices in the South warrant the belief that wood of this quality can be profitably distilled. It is better to split out and reject the low-grade wood. While a large proportion of the yellow-pine stumps in Idaho con- tain a certain amount of resinous wood which is as rich as the truly pitchy stump, such wood forms so small a proportion of the entire stump that its removal from the nonresinous wood is prohibitively expensive. The case is similar to that of many ore-bearing forma- tions in which the valuable mineral is disseminated through so large a proportion of worthless material as to make its concentration in a form rich enough for treatment commercially impracticable. At the 1915 prices for raw material and for products, wood from 60 to 80 per cent of which must be split off and rejected, or wood which will yield but 6 gallons of turpentine or a total of 30 gallons of resinous products a cord, could not be profitably distilled. When the nonresinous portion of the stumps has rotted away, leaving only the resinous heart, this material, which then would be similar to the rich stumps, could, of course, be profitably used, provided the ratio of cost to selling value remained essentially the same. Future careful studies of the uses to which the heavy crude oil may be put probably will result in a revision of the price here as- signed to it. That of 15 cents a gallon is based on its probable value for uses to which certain of the creosote oils are being put. Undoubt- edly its value can bo enhanced by suitable refining methods, or by working it up into special products. These would necessitate addi- tional equipment and labor, thus increasing the manufacturing cost, the probable expediency of which can not be foretold. The same con- DISTILLATION OF STUMPWOOD. 51 sideration applies to the light-oil fraction. From the prevailing price of articles with which such refined or special products must compete, it is doubtful if the balance between production cost and market value of the output of a plant would be materially affected thereby. The acetone, wood alcohol, and acetic acid content of the aqueous distillate is, roughly, one- fourth that obtained in the crude distillate from hardwood plants. The value a cord of the alcohol and acetic acid recovered as acetate of lime, based on 1915 prices, is approxi- mately $1 and $1.50, respectively. The crude liquor as obtained from the retorts is so heavily charged with tarry bodies that the acetate if obtained therefrom by the ordinary method is of a low grade and at best usually commands too low a figure to make its recovery profit- able. Even by some improved processes, the recovery of these three products, which would increase the gross income by about $2.50 a cord, could be accomplished at best only on a narrow margin of profit, and the earning power of a plant thus equipped would not be ma- terially increased by so doing. A company in the Northwest, oper- ating a wood- distilling plant on selected Douglas fir mill- waste, in- cluding the recovery of these products in their margin of profits, found the enterprise, as then carried out, unprofitable. One other possibility needs to be mentioned. It has been stated that lean and also medium resinous stumps contain small propor- tions of heartwood nearly if not quite as rich in resin as the resinous portions of rich stumps, but the proportion of such wood is so small that the cost of splitting it out would be prohibitive. Should the nonresinous portion rot off the lean and medium stumps in the course of a few years, as happens in the longleaf yellow-pine cut- over lands, the remainder or heart of the stump would then be prac- tically 100 per cent resinous and suitable for distillation. Unfortu- nately, few such rotted stumps showing only the sound, rich heart were observed in any of the districts visited. The rotting off of the sapwood would unquestionably proceed more rapidly farther south. RELATION OF WOOD DISTILLATION TO LAND CLEARING. One of the purposes of this investigation was to secure informa- tion on what part of the cost of clearing land for farm purposes might be paid for by distilling the wood or by selling the wood for distillation. The cost of clearing land for farming in the Pacific Northwest varies widely, depending on the size, number, and age of the stumps, the lay, nature, and water content of the soil, cost of labor and ma- terials, and other factors. The United States Department of Agri- culture, in cooperation with the State agricultural experiment sta- tions of Washington, Wisconsin, and Minnesota (11), and the Uni- 52 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. versity of Idaho (8), have done much actual work on land clearing in this section, and have found the cost of clearing for farm purposes to vary from $50 for the lightest clearing ground to $150 an acre for heavily wooded hardwood land. In the sections from which samples were collected 20 yellow-pine stumps to the acre is a high average on land where the stand is mostly or entirely yellow pine ; under more commonly occurring con- ditions in which there is more of a mixed stand, such as in the Pot- latch-Deary district, 10 to 12 yellow-pine stumps to the acre is more nearly correct. If, as indicated by these investigations, 10 per cent of the yellow- pine stumps are of the rich, resinous type, yielding 20 gallons of turpentine and other products in proportion a cord, or 15,4 gallons a ton, the 12 stumps an acre would yield 1 cord, and 20 stumps about 2 cords of wood an acre. If the wood could be disposed of for $10 a cord, the return for the extra labor, time, and expense required to split and sort out the resinous wood and haul it to a shipping point would be from $10 to $20. Experiments in clearing 1 acre carrying 12 yellow-pine stumps. varying from 2 to 5 feet in diameter (page 18), have shown that this return will a little more than pay for the powder needed to blast out all the yellow-pine stumps. In other words, provided a market for the wood at $10 a cord is available, the net cost of land may be reduced from (>J to 40 per cent, less the cost of sorting and hauling to a shipping point. The chief question is whether a farmer can afford to shoot all the yellow pine clear of the ground, or crack with explosives and pull the pieces with a puller, then sort the wood and haul it to the rail- road, or whether he can get his land cleared more cheaply by using some of the methods of burning described in Idaho Agricultural Ex- periment Station Bulletin 91, or United States Department of Agri- culture Farmers' Bulletin 974. If the returns from the fat stumps on a tract are sufficient to justify the more expensive methods of clearing, and it is some advantage to have all the roots out of the ground, blasting is the method which will be most used. About 100 pounds of explosive would be required to shoot clear of the ground all the yellow-pine stumps on an acre, while 25 pounds would crack them enough so that they could be bunted. In the first case, the cost of explosive (1914-15) would be about $15 and in the second case $4. The explosive could be placed with a little loss work if the stumps were to be burned. Possibly it would require about the same amount of labor to burn the stumps in the ground as it would to sort over the pieces, burn those unfit for distillation purposes, and haul the rest to the railroad. On the assumption that it would, it DISTILLATION OF STUMPWOOD. 53 will be seen that the farmer would just about break even if he could sell the rich wood for $11 an acre. A wood- distilling plant of any size can not operate profitably with- out an ample and steady supply of rich wood extending over a num- ber of years. For this reason a wood-distilling plant should be built and conducted as an independent business rather than primarily as a means of meeting the cost of land clearing. Naturally, it would be located with reference to available material ; that is, where there was land ready to be cleared. Such wood as the settlers could supply would be simply an addition to the stock, though in some instances the bulk of the wood might be obtained from this source. In the Winchester and Craig Mountain country, where the condi- tions are quite different from those observed in the other sections, there is a close almost pure stand of yellow pine. As there are no heavy underbrush or slashings, clearing such cut-over lands consists practically entirely in burning the tops of the cut trees and removing about 20 large yellow-pine stumps. The comparative absence of younger growth between the trees, fairly even surface of the country, and uniform stands, of which per- haps 40 per cent of the stumps are quite rich or resinous, make such sections possible localities in which the cost of land clearing may be met, in a large part at least, if not entirely, by distilling the stumps. SMALL, SEMIPORTABLE WOOD-DISTILLING PLANTS. Wood-distilling plants as usually constructed where the daily capacity varies from 10 to 100 <3ords of wood, are permanent, especially when a number of products are made and refined for mar- ket. Furthermore, such plants require capital for financing and technical skill and experience for profitable operation. Therefore, wood-distilling plants would be comparatively few, and small plants of about 1-cord capacity that can be set up, torn down, and re- located at will would be useful, particularly in sections removed from railroads and where transportation is difficult. Especially would this be true if the mixed crude oil and tar obtained could be profitably disposed of to refiners or directly to users. Since the work described in this publication was completed, private companies have built and operated such small plants. Plants of this kind, of 1-cord capacity, can be built for from $3,500 to $4,500. They might be bought and operated by a community, the crude oil being sold direct to the zinc, lead, and copper miners, who use it for the concentration of ores by the flotation process. The cheap, semiportable 1-cord retort is probably better adapted to Northwest conditions than are the large, more permanent, and more expensive plants making and refining a number of products. 54 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. USE OF OIL FOR ORE FLOTATION. Of the many oils that have come into use for ore flotation, oil of eucalyptus, costing about $1.50 a gallon, is prized most highly. Next in the order of merit come the pine oils, selling for from 40 to 60 cents a gallon. In the effort to discover cheaper oils, most of the wood creosotes, as well as many coal-tar creosotes, have been found to be acceptable. They range in price from 15 to 30 cents a gallon. Producers of petroleum have also entered the flotation field, though with but limited success when petroleum alone is used. Better results are obtained by mixing a small amount of pine or creosote oil with the crude petroleum. "Kerosene sludge acid" from California oils, obtained by treating the crude oil with sul- phuric acid in the refining process, is also being sold for flotation. The sludge acid from coal tar is said to have a flotation value as good as or better than that from petroleum, and even coal tar itself is extensively used because of its low price. These different products entering into ore flotation may be divided, in a general way, into two classes, known as " frothing agents," which promote foaming, and "collecting agents," the function of which is to coat with a film of oil the mineral particles only, so that, adhering to the air bubbles in the foam, they are thus sepa- rated from the gangue. While all oils possess both frothing and oiling or collecting properties in some degree, eucalyptus oil, the pine oils, pine-tar oils (the "light" and "heavy" oils of this pub- lication), and crude turpentine are primarily used as frothing agents. Coal tar, pine tar, together with hardwood tar, and " sludge acid " are used as collecting agents. Success in ore flotation demands a proper adjustment of these two physical properties to the particu- lar requirements of the ore to be treated. While all of the products mentioned can be used in proper combination, with some measure of success, the pine oils occupy a commanding position in the field of ore flotation. Samples of pine oil and of the crude distillates obtained in the retort work were submitted for flotation tests to the Bureau of Mines Metallurgical Experiment Station, Salt Lake City, Utah, to ore mills in the Coeur d'Alene district, and to the testing department of a large copper mining company. The results from their tests showed that the crude turpentine was virtually as effective a flota- tion agent as the pine oil, and even the light and heavy oils were applicable, though requiring a greater proportion a ton of slime, especially in the case of the heavy oil. Even the acid liquor was found useful on certain pyrite ores. Where, therefore, the efforts of the producers were formerly di- rected toward refining the crude distillate to recover a maximum DISTILLATION OF STUMPWOOD. 55 quantity of turpentine, the change in market conditions makes it desirable to throw as much of it into the pine-oil fraction as is possible, or to go a step farther and market the entire crude dis- tillate as flotation oil. If this were done it would, of course, re- duce decidedly the cost of running the plant, and simplify opera- tion. The consequent reduction in cost of production would prob- ably amount to $2 or $3 a cord. As to future flotation-oil values it is difficult to conjecture. The Bureau of Mines, which experimented with the various oils obtained in the course of this work, commenting on the conditions that will probably have to be met in the flotation-oils market during the coming years, points out that : Pine oil at 50 to 60 cents per gallon has cost too much. Crude petroleum and coal tar containing small additions of pine oil can be made to do almost the same grade of work and are hence cheapening the cost of flotation oils. Pine cresote, pine tar oils, and various hardwood fractions, together with hardwood tar, are finding acceptance in place of the more expensive products. There will always be a market for pine products, however, as long as they do not cost too much; 30 to 40 cents per gallon, f. o. b. the West, will probably be the price paid for such material and when the price goes much above that, the material will merely be eliminated from consideration. Some idea of the quantities of these pine products used in the flota- tion of ores may be obtained from Table 20. TABLE 20. Monthly consumption of flotation oils in the United States (1916). [Compiled from a report of the Bureau of Mines.] Type of ore. Monthly tonnage of ore. Wood products. Beginning of 1916. End of 1916 (esti- mated). Pine oil.i Pine- tar oil.2 Oil of eucalyp- tus. Wood creosote. 3 Crude turpen- tine. Copper Tons. 1,248,000 248,000 115,000 45, 700 Tons. 1,942,000 350,000 136,000 123,000 Galls. 7,800 8,000 515 1,300 GaTls. 95 85 Galls. Galls. 47,600 30,000 13,800 4 600 Galls. 205 450 Zinc and complex . Lead 28 Gold and silver... 95 Total 1,656,700 2,551,000 17,615 275 28 96,000 655 1 Probably includes a considerable amount of the lighter fractions of pine-tar oil. 2 The crude light oil would probably come in this class. 3 The crude heavy oil would probably come in this class. It has been pointed out that combinations of different oils are used by mixing the more expensive pine- wood distillates with crude petroleum, coal tar, etc., in suitable proportions to obtain the de- sired foaming and collecting effect for the kind of ore to be treated. While this is to a large extent done at concentration plants, some pro- ducers in the East market blended oils on this same principle. This should, of course, be given careful consideration by those-who may 56 BULLETIN 1003 U. S. DEPARTMENT OF AGRICULTURE. engage in the production of flotation oils from resinous wood wastes in the Northwest. A list of uncompounded pine oils and other dis- tilled wood products used, either alone or for producing blended oils for flotation, is given herewith. Some idea of the required proper- ties may be derived from the specific gravities : Crude pine oil. Pine-tar oil, double refined (sp. gr., Crude wood turpentine. 0.965 to 0.990). Pine oil, steam distilled (sp. gr., 0.925 Pine tar, thin (sp. gr., 0.980 to 1,0