Northrop, E. B.; Chittenden, H. A., Jr. (ed.) / The Wisconsin lumberman, devoted to the lumbering interests of the northwest
Preservation of wood. The thilmany process to impregnate wood with sulphate of copper and chloride of barium, pp. 474-475 PDF (681.8 KB)
The WMconsin Lwmberman. PRESERVATION OF WOOD. o The Thimanyu roons to inpr lte Wood 0 With Silpt of copper and Chloride of tA Barium. 6 The great and constantly increas- o ing extent of our wood pavements de- t mands that every person interested s in its permnanence should give atten- c tion to the best and most economical a mode of preparing the same. c It is well known that the se-alled d "Nicholson Pavement," where the blocks are only dippedin coal tar, c has proved a failure in all our cities. In some, where the " Nicholson" has c been laid in the ordinary manner, it I shows, at the expiration of three or E four years, alarming signs of decay. In fact, no wood can be made to last 4 any great length of time, unless the I preserving substance is made to per- X meate thoroughly the pores of the wood, and as the coal tar cannot pen- etrate the wood, but merely covers the surface, it will be seen that, as soon as this coat is worn off the wood has no protection whatever, and will quickly decay. From dipping the blocks into coal tar results another great disadvantage. Generally we have to use blocks for paving, which are not thoroughly seasoned. By dipping such blocks into coal tar, the external pores are closed, the water or sap cannot evaporate, and decay will shortly take place. Matters grow worse as soon as the external coal tar coating on the surface of the street is worn off. Then the water can freely, enter the pores at the top, of the blockbut cannot be discharged at the bottom of the same because there the pores are still closed. The really preserving substance of oal tar is creosote, a light, ethereal il, which evaporates at a very low tmperature. The remaining con- tituents of the coal tar, consisting f greasy substances and minute par- icles of coat cannot enter into the mail cellular tissue of the wood, be- ause of their tough, syrupy nature and form, as stated above, a surface coating, which can only accelerate Lecay. Let us examine the wood and its constituents. Wood, in its chemical combination, consists of a fibrous substance and a iquid filling up the interstices, called sap. The clear wood fibre, as dem- onstrated by chemistry, is composed Af 52. 4 parts carbon, 41.9 parts of Oxygen, and 5.7 parts of hydrogen, and is the same in all the different varieties, but the sap of each kind of wood contains a great many different substances; in pine the resin pre- dominates, and the oak is well known for the superiority of its tanning qualities. Some varieties contain glutinous and saccharine matter, while from others we extract coloring pigments, salts and mineral sub- stances, all soluble in water. Chem- istry shows that it is almost impossi- ble to destroy the clear wood fibre, and that it can be done only by the strongest acids or alkalies. Wood, free from sap, will not de- cay for a very long time, even when put in the ground or exposed to rain or dampness. The cause of its de- cay, when so exposed, will be simply found in the different substances of which the sap is composed; its'albu- men parts act as yeast for all the oth- ers, and excite fermentation, which 474 I I t I I I s 1!. I I , I C I .
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