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Special elevators are designed for barrels, boxes, trays, etc. The elevator for barrels is shown in Fig. 35. It consists of two chains, to which are attached arms slightly curved to hold the barrels. The barrels are run on to the elevator down an incline from the belt conveyor. They are then carried to the proper height by the elevator and discharged from the head pulley on to another incline which carries them to another belt conveyor and to the desired point. Box and tray elevators usually consist of small platforms or shelves, swung or hinged between two chains, as shown in Fig. 36. The boxes and trays are usually placed on the elevator by hand and removed by the same means. These latter elevators are much used in breweris for cases of bottles, etc.

A Specification for Coal-Tar Creosote.

A specification for coal-tar creosote proposed some years ago by Messrs. von Schrenk, Fulks and Kammerer, of St. Louis, is brought to attention by them in a paper in the November, 1907, Bulletin of the American Railway Engineering and Maintenance of Way Association. The specification is as follows: "The oil used shall be the best obtainable grade of coal-tar creosote; that is, it must be a pure product of coal-tar distillation and must be free from admixture of oils, other tars or substances foreign to pure coaltar; it must be completely liquid at 38 deg. C., and must be free from suspended matter; the specific gravity of the oil at 38 deg. C. must be at least 1.03. When distilled according to the standard method, that is, using an 8-oz. retort, asbestos covered, with standard thermometer, bulb 1⁄2 inch above the surface of the oil, the creosote, calculated on the basis of the dry oil, shall give no distillate below 200 deg. C., not more than 5 per cent below 210 deg. C., not more than 25 per cent below 235 deg. C., and the residue above 355 deg. C., if it exceeds 5 per cent in quantity, must be soft. The oil shall not contain more than 3 per cent water."

Barytes is used for the manufacture of paints, porcelain, and as an adulterant and filler in paper and other industries. The principal producers are in Tennessee, Virginia, and North Carolina. The average price is $4 per short ton for crude ore. The raw material is first ground and then bleached with sulphuric acid, after which the product is worth about $18 per ton. The two most objectionable impurities are iron and calcite. Limonite is often associated with barytes, and this must be removed for paint manufacture, while calcite absorbs much acid, and hence is detrimental. The separation of barytes from the impurities has been effected by acids, but jigging is cheaper and the difference of specific gravity of baryte and calcite or gypsum, which are commonly associated, make this form of separation cheap and efficient. This method of separation will probably find wider application in the near future.

TURPENTINE FROM WASTE WOOD.'

By J. E. TEEPLE, PH.D.

Director, The Industrial Laboratories, 164 Front St., New York, N. Y. The name turpentine is stated to be of Persian origin and was probably first applied to the resinous exudation from some member of the sumac family. It is now confined to the resinous exudation of the conifer family, more particularly those of the genus Pinus, the pine proper. During recent years, efforts have been made by interested parties, and particularly by some of the state legislatures, notably those of Georgia and New York, to restrict the name turpentine and oil (spirit) of turpentine to the resins and their distillates coming from the live tree as opposed to distillates of resins from waste wood. But this attempt has not met with general approval.

What may be called the old process oil of turpentine, or gum spirits of turpentine, is derived mainly from southwestern France, northwestern Russia, and southern United States. In the United States the most productive tree is Pinus palustris, or long leaf pine, although the Cuban loblolly pine, and in many cases, even the short leaf pine give paying yields. In France, the pinus maritima, and in Russia, the pinus sylvestris are the trees most commonly worked. The well-known procedure in the United States is to prepare the tree by "boxing," i. e., cutting a receptacle in the base and "facing" or preparing this receptacle for the gum. Then every week throughout the turpentine season, during the summer months, the tree is subjected to the hacking process, which consists in inflicting a fresh wound by cutting off a narrow section of the bark and outer sap wood of the tree. This process of wounding the tree has two effects. First, there is an exudation of the normal sap of the tree which might be compared to bleeding when an animal is wounded; and second, there is a pathological production of resinous material in the neighborhood of the wound which might be compared to the formation of a scab. This latter material probably makes up the greater part of the flow of gum, and to keep the process in operation it is necessary to re-wound the tree every week. As the resinous material flows out from the tree into the boxes, it is dipped at intervals of about three weeks, and conveyed to stills where distillation with water or steam drives off the spirit of turpentine, amounting to approximately 20 per cent of the total, and leaves the non-volatile material, which after drying and filtering, becomes the rosin of commerce. The yield from any tree depends on the season, weather, vitality of the tree expanse of tree top, etc., and as the vitality is certainly decreased by the system of boxing, the cup and gutter

'Journal Society of Chemical Industry.

system which obviates boxing has been coming into more extensive use within the last few years. This is a modification of a system that has been in use in France for over forty years. The greater part of the resinous material from the tree may be looked upon as a pathological product resulting from the wound, and not a normal product of the tree. Wounding a tree causes the formation of quite a large number of rosin ducts in the neighborhood of the wound, which gradually become stopped up with the resinous exudation, so that when a tree has been worked for several years, the whole body of the tree up to a height of 10 to 15 feet, or at least as high as it has been chipped, becomes thoroughly saturated with this resinous material, which apparently does not differ in any appreciable degree from the resinous material that has been collected in the boxes, excepting that it contains a smaller percentage of spirit of turpentine and a larger percentage of rosin. This wood saturated with the resinous product from the tree is known as "light wood," and when we consider the rapidity with which turpentine orchards are disappearing, it is obvious that we must look to light wood as the future source of turpentine. When a tree is blown down by any of the frequent winds, or dies from loss of vitality, due to boxing, the sap wood rots away, leaving this light wood and the heart of the tree thoroughly saturated with resinous material, and capable of resisting the action of the elements for decades. Roots and stumps also become rich in these resinous products, and they were the first to be utilized in North Carolina, for the production of pine tar, by distillation. It soon became evident that there were considerable quantities of turpentine in the pine stumps, and many attempts were made to recover this, the earliest patent dating as far back as 1841. Very little was accomplished in a commercial way, however, until a plant was built in 1872 at Wilmington, N. C., for the destructive distillation of "light wood" and stumps. "Light wood" is exceedingly heavy, weighing 4,000 or 5,000 pounds per cord, and probably derives its name from the fact that it is particularly desired by the negroes for making their fires and for use as torches. When distilled, it should give all the products of "hard wood," viz., charcoal, acetic acid (recovered as acetate of lime), wood alcohol, gas and tar; but the tar being "pine tar," is much more valuable than the corresponding product from hardwood, and there is a much larger yield, due to the production of tar from the rosin present. In addition to all these products, there are obtained from 6 to 30 gallons per cord of spirits, depending on the quality of the "light wood." The tar, by further distillation, produces pitch, which finds a steady market, and tar oil, which, on account of its creosote contents, is worked up into disinfectants, cable-coating, sheep dip, wood preservative, shingle stain, etc. There is also a varying vield of wood oils, which find some market in the drug and essential oil trade. By basing their estimates of production of charcoal, acetate of lime and wood alcohol on the yields commonly known to be obtained from "hard wood," and for those of oil of turpentine, tar, tar oils, and "specialties" on

the richest stumps and "light wood," it was easy to show on paper at least, a net profit of $50 per cord, which in a plant of ten cords per day meant $500 daily profit. With some such figures as a basis, a great many people were persuaded to embark in the destructive distillation of "light wood," but as soon as these plants were under way, a great many drawbacks appeared. (1) Their yield of wood alcohol proved to be only one or two gallons per cord, instead of ten gallons per cord as commonly obtained from hard wood, and the cost of manufacturing wood alcohol from this source was found to be considerably in excess of the selling price. (2) The acetate of lime produced, was found to be comparatively small in quantity and poor in quality, the usual product being a brown acetate, which commanded a very much lower price than the regular commercial gray acetate, produced from hard wood. (3) The yields of oil of turpentine fell far below the estimates in most cases, and proved to have a very strong odor of creosote and aldehyde products, and great difficulty was found in marketing it at a satisfactory price. The objectionable odor could be removed in the main by treatment with sulphuric acid and caustic soda, but the yield was very much decreased by this treatment, and the resulting product, while having a fair odor, had lost noticeably in the valuable drying properties. (4) The various "specialties," from which so much was expected, usually overstocked the market after the first few gallons were sold. (5) The charcoal was ordinarily produced far away from blast furnaces, where the only consumption was that required for domestic heating in some not too distant city.

Many of these plants were finally abandoned; many more were accidentally burned; some are still standing practically in ruins. One which was built not many years ago at the cost of about $200,000, was sold as scrap within the last year for $20,000 or less. Of course, vigorous attempts were made to overcome the various defects, such as heating very gently until the spirits of turpentine had been distilled off and then increasing the heat; taking off the various products at different levels in the retort; regulating the heating by various devices, so that it should be evenly distributed throughout the retort; installing a great variety of patent separators to make the refining easier and more accurate. A few such plants are still in operation. The claim of some to be running at a financial profit, is probably due to the fact that these particular plants have worked up their tar oil into secret special compounds for which they have found a market.

So far as the writer knows, none of them is attempting to make wood alcohol; one at least is still making acetate of lime, and showed recently a net profit of Ic per cord and a capacity of 7 cords per day. One small plant is using an asbestos-covered vertical retort in an endeavor to regulate the heat; another attempted to accomplish the same object by surrounding the retort by a huge oil bath. In the latter case material lying nearest the sides of the retort is charred before that in the center has been warmed up appreciably. The retorts used have been mainly of iron, varying in size

from half a cord up to five cords capacity, and requiring from 36 hours to 5 days for the distillation of a single charge.

It seems to be evident from the above that primary destructive distillation is not the proper method to apply from a financial point of view. The use of a hot bath in the retort instead of round it was patented by Johnson in 1865. This idea has been re-discovered and re-patented within the last three or four years, and at least three plants working on this system are now in operation. The method usually adopted is to charge the retort with wood and then pump it nearly full of melted rosin, keeping the temperature of the rosin sufficiently high by blowing in superheated steam. When steam is allowed to blow through, it carries off the spirits of turpentine and with it a certain amount of wood oil and rosin oil. It has been stated that the yields from this process are as high as 30 gallons of spirits of turpentine and 40 gallons of heavy oil and rosin oil per cord, but in tests which the writer has witnessed, from 12 to 15 gallons of spirits of turpentine, 2 to 3 gallons of oil and 5 gallons of rosin oil might be considered average figures. The defects of this system are obviously danger of fires and high cost of the process.

The next system to be generally exploited was the use of superheated steam, for which the oldest patent was granted to Hull in 1864. This process has been repeatedly re-patented since, and there are now at least 6 such plants in operation. The usual method is to grind the wood in a chipping or edging grinder, place it in fairly large vertical retorts, and pass superheated steam through it until the spirits of turpentine and some of the oils have been entirely distilled off. In ordinary practice the superheaters are not regulated accurately, and the fires are very often allowed to die out. The method seems to have no particular advantages, and has the decided drawback of charring the wood where the superheated steam first enters the retort and so contaminating the spirits of turpentine with products of destructive distillation.

The first patent for removing the oil of turpentine from "light wood" by the use of steam without superheating was granted to Leffler in 1864. This apparently received no consideration for a great many years, and was rejuvenated by Krug a few years ago. Most of the plants which have recently been built, have used primary steam distillation to recover the spirit of turpentine, postponing destructive distillation or any other methods of recovering the other products from the wood until the spirit was removed. Future developments will probably be along similar lines. The principle used in this method is quite different from that of all the other systems, which heat the product in the wood high enough to boil off the spirit of turpentine. The success of a steam distillation plant depends first on the quality of wood; second, on the price for which it can be delivered at the retorts; third, the keeping of labor costs at the lowest possible figure by use of suitable retorts and machinery; and fourth, the proper penetration of the steam into the

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