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Pursuant to the foregoing notice, the stated semi-annual meeting of the Association was held at the Massachusetts Institute of Technology, Boylston Street, Boston, on Wednesday, Oct. 28, 1891, at 10 o'clock A M.
The President, Mr. WALTER E. PARKER, occupied the chair.
The President submitted the following nominations of new members, recommended by the Board of Government, foi election :
The foregoing names were then voted upon separately, and each nominee was duly elected to membership in the Association.
The President then introduced Col. James Francis of Lowell, Mass., who read the following paper :
METHODS OF PRESERVING TIMBER IN SITUATIONS
WHICH EXPOSE IT TO DECAY.
BY JAMES FRANCIS, LOWELL, MASS.
The perishable nature of wood, especially when placed in situations where there is an excess of moisture in the surroundings, has led to many experiments with a view to discover a process of treating timber with salts or oils, that would preserve it from decay.
Dry rot, sometimes called saprot, the most formidable disease to which timber is subject, is commonly attributed to a combination of the acids found in the sap with the oxygen of the air, which produces fermentation followed by decomposition. Unseasoned timber, placed in damp situations with but partial ventilation, will soon show signs of dry rot.
Beams which presented the appearance of being sound on the outside have been found completely rotten inside. The shell remains sound because it becomes seasoned, and relieved from the sap.
Wet rot, as distinguished from dry rot, is considered to be occasioned by alternate exposure to moisture and dryness, beginning at the surface of the timber and working inwards. Piles and other timber placed in salt or fresh water will show signs of wet rot at the water line, before it attacks other parts. Posts, set in the ground, first begin to rot at the ground line.
Among the earlier investigators on the subject of preserving timber may be mentioned Johann Glauber, the famous chemist
, of Carlstadt, Germany, who in 1657 experimented with vegetable tar and pyroligneous acid; the wood having been first carbonized by the action of fire, then covered with a coating of
tar and immersed in pyroligneous acid. Since then up to 1846 no less than forty-seven different processes, adapted for the preservation of wood, are recorded, besides others of more recent date. Of these processes many of them would, no doubt, prove effective, provided they could be carefully and economically applied. It is a difficult problem to treat timber in large quantities and meet with reasonable success.
The condition of the timber that is to be treated should always be considered. It should be sound. The trees should be cut during the season when the least amount of sap is flowing, which in this section of the country is in winter, say from November to February. It should not be treated in a frozen state, and it is advisable to shape the timber to the form in which it is to remain, before the treatment is applied. Seasoning is a very important factor. A few months of exposure to the air and sun will materially add to the durability of the wood. The process of treatment must be rigidly and faithfully performed. The opportunities for gross frauds which cannot readily be detected are many, and the numerous instances of record where cheating has been systematically carried on at works established for the purpose of treating timber, prove that the safest course for parties using preserved timber is to do the work themselves.
Three of the well-known processes for preserving timber are the following, viz. :
Creosoting, creosote oil, so called, being the antiseptic.
Creosoting. The creosoting process consists in injecting timber with hot creosote oil, in a closed cylinder, under pressure. invented in 1838 by John Bethel of England, who found that, by forcing at least seven pounds of creosote oil into each cubic
foot of timber, the process was satisfactory for railroad ties and other railway work, but that for marine work it was better to have not less than ten pounds per cubic foot. In this country experimenters have used from ten to twenty pounds of creosote oil per cubic foot, and the estimated cost is from twelve to twenty-four cents per cubic foot, or ten to twenty dollars
thousand feet board measure. Creosote oil, such as is most commonly used in this country and abroad for the treatment of wood, is distilled from coal tar. It is a heavy oil which will sink in water, and contains carbolic acid, creosote and other constituents, considered essential for the preservation of wood.
Wood creosote oil is distilled from wood tar. It is a lighter oil than that distilled from coal tar, and its cost is less. It is but slightly soluble in water, and is not a specific poison. An oil distilled from the heavily resined pine wood found in the Carolinas has been used since 1885, for the treatment of piles and timber, by the Carolina Oil and Creosote Company of Wilmington, North Carolina, who claim that the wood creosote oil possesses much better antiseptic qualities for preserving wood than exist in the heavier oil obtained from coal tar. This Carolina oil weighs about eight and one-half pounds per gallon.
Creosoting, for many situations and conditions, is considered the most perfect process in use, and it is the only effectual agent known that will preserve wood against the attack of the marine worms, Teredo and Limnoria, which are found along the Atlantic coast, and are confined strictly to salt water.
Naturalists have carefully studied the mechanism and habits of the Teredo. They find that the worm, when young, penetrates the wood by a very small opening, under the surface of the water and usually near the surface of the ground, then changes its course in order to follow the direction of the fibre. It feeds and grows in the wood, and the length of its hole, which in some cases reaches sixteen to eighteen inches and even longer, represents about the length of the worm. It never enters the wood beyond its length, being dependent upon having its tail end in the clear salt water, outside of the wood, through which it is believed the Teredo receives its nourishment from the animalculæ in the sea water. Myriads of these worms, varying from one-twenty-fifth of an inch to one-fifth of an inch in diameter, at work in the heart of a driven pile, quickly perforate and destroy it. The Royal Academy of Science in Holland reported upon the means of preserving wood from the Teredo in 1866, as follows:
“ The only means which can be confidently regarded as a preservative against the ravages of the Teredo is the creosote oil; nevertheless, in the employment of this agent great care should be taken regarding the quality of the oil, the degree of penetration and the quality of the wood treated.”
The creosoting works of the Old Colony Railroad Company, situated at Somerset, Mass., are employed mainly for treating the oak piles of the company, used in and about Fall River, to guard against decay and the ravages of the Teredo that swarm in that section of Taunton River. These works have been conducted for many years with reasonable success, and to such an extent as to repay them for the outlay and the trouble.
The Limnoria, another very destructive worm or grub, is found along the shores of New England. It is less than a quarter of an inch in length, and burrows into the wood to a depth of about one-half an inch ; and when numerous it will quickly reduce the wood to a series of thin partitions between the burrows, which after a while become broken and washed away by the action of waves. The new surface is at once attacked, and the work of destruction goes on until the wood is entirely eaten away.
Sometimes the Limnoria and the Teredo are found in the same structure, — both working under
, water, the former eating from the outside, while the Teredos penetrate and honeycomb) the interior.
Creosoting is far from being a cheap process, and for this reason perhaps more than any other it has failed to be exten