8

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 animalcule 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

sively adopted in New England. Creosoting meets with favor in England, and at the present time it is the only process that is carried on there with any degree of magnitude and success.

Burnettizing.

Burnettizing was introduced by Sir William Burnett of England in 1838. The invention consists in destroying the tendency of certain vegetable and animal substances to decay, by submitting them to the action of chloride of zinc. The degree of dilution recommended by Burnett is one part by volume to fifty parts of water. The method of impregnating the wood under a pressure of seven to eight atmospheres, as is done in the creosoting process, is most commonly used. The cost of burnettizing is about one-half as much as creosoting, or, say, from five to six dollars per thousand feet board measure.

There are no burnettizing works of any extent in New England, at the present time. Some of the railroads in various parts of the country have experienced good results from the burnettizing of ties, especially ties of soft wood, such as pine, tamarack, hemlock and cedar. Among them may be mentioned the Rock Island & Pacific Railroad, the Lehigh & Susquehanna Railroad and the Vermont Central Railroad.

The process was introduced at Lowell in 1850, and conducted faithfully for about twelve years, during which period a very large amount of timber was burnettized for bridges and for other structure purposes in exposed situations. But the results were not always satisfactory to Mr. Francis, under whose supervision the works were built and conducted, a process was abandoned.

In Germany burnettizing meets wi Stuttgart Technical Convention of 15 lows:

"As the experience of those rail five to twenty-six years impregn zinc, under pressure, after steam

1862 the

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The If as fol

twent ride

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has been very satisfactory, and as this system costs only onehalf to one-third as much as impregnation with creosote or corrosive sublimate, the majority of railroads have adopted the chloride of zinc process."

Steaming the wood under a pressure of sixty to seventy pounds per square inch, as done in Germany, preparatory to burnettizing, no doubt adds to its durability. Tredgold considers that steamed timber shrinks less and stands better than that which is naturally seasoned. Barlow, another good authority, is of opinion that the seasoning goes on more rapidly after the piece is steamed. If steaming had been done in Lowell, in connection with burnettizing, it is very probable that the results would have been more satisfactory.

Kyanizing.

This process was invented and introduced in England, in 1832, by John Howard Kyan. It consists in steeping the wood in a solution of corrosive sublimate, and the degree of dilution is usually one pound of the salts to ninety-nine pounds of water. It is a very slow process, compared with those in which the wood is impregnated under a pressure, and requires about as many days for treatment as creosoting or burnettizing would require hours. The usual rule in this vicinity is to allow the timber to steep in vats for a length of time depending upon its least thickness: thus, if the timber is ten by twelve inches thick, it would remain in the vats eleven days; if six by nine inches, it would steep seven days. In Baden, timber ten by twelve inches would remain in vats eighteen days, and if six by nine inches, ten days. Bichloride of mercury, which is the antiseptic in this process, contains muriatic acid, which acts upon iron; and it is found impracticable to attempt to impregnate the wood under a pressure in iron cylinders, as can be done when creosote oil or chloride of zinc is used.

Kyanizing was introduced at Woolwich, England, by the

Royal Engineers, in 1836. Captain Alderson of the Royal Engineers about that time reports a case as follows:

66

"I was informed of the return of the ship Samuel Enderby' (four hundred and twenty tons, built at Cours in 1834), as having been built entirely of saturated timber (kyanizing process), the same process having been also applied to the sails and rigging. It was said she had returned in a state of decay, and that the experiment was a complete failure. I lost no time in going on board and inspecting her, as well as in making inquiries as to the health of the crew. The mate informed me they had all been quite healthy, that no death had occurred during the twenty-nine months they had been absent, and that since May last they had not had even a medical man on board. I next examined the bilge water; it was without any unpleasant taste or smell, excepting what arose from the oil that floated on the surface, the ship having a full cargo of sperm oil. On examining various parts of the timbers of the vessel, from the upper deck to the keelson, they were perfectly sound. The mate said he considered the vessel as sound as the day she was launched, and a very tight ship. With respect to the sails and rigging, however, he said they had not answered as well as was expected; and on enquiring at Mr. Enderby's manufactory, where they were made, I found it was not the first time this had occurred, where the canvas had been constantly exposed to the light, though it had invariably succeeded under the most nfavorable circumstances and situations, where light was exe ed or only partially admitted."

Mr. James B. Francis, who has given a great deal of study to this subject, was sent to England in 1849 by t manufacturing companies of Lowell, to obs re the in use there for preserving timber from de; and 17, 1849, he examined the same ship, "nel E then in port at the West India Docks, Bl wall. was empty and had been in port about moni found very few signs of decay, and was ined by

wright who was with him that he considered her in much better order than is usual in ships of her age. The ship was then fifteen years old.

Professor Faraday, lecturer at the Royal Institution, London, explained in one of his lectures in 1833 that the preservation of the wood arises from a chemical combination which takes place between the corrosive sublimate and those albuminous particles which Berzelius and others of the highest authority consider to exist in, and form the essence of, wood; which, being the first parts to run to decay, cause others to decay with them; also, after witnessing various trials, extending to five years, in the fungus pit at Woolwich, in all of which the prepared timber and canvas came out perfectly sound, whilst the unprepared were decayed, he gives his opinion that the process would be found effectual in preserving timber, and that the improvement would be so great as fully to justify its extensive application.

Professor Faraday experimented upon the penetration of the solution into the wood by the application of hydrosulphuret of ammonia, which will turn black on meeting with mercury. In a cube of elm he traced the corrosive sublimate to the depth of from one-fifth to one-fourth of an inch; in a cube of oak, one-fourth of an inch; in a cube of fir, from one-eighth to onesixth of an inch. In the latter, the resin in the wood had probably offered the obstruction to penetration.

Plate I. illustrates an experiment recently made in Lowell on the penetration of the mercury, in a section of two-inch spruce plank kyanized in 1890. The dark shaded part around the edge shows the penetration of the mercury as indicated by the application of a few drops of hydrosulphuret of ammonia. The penetration can be easily traced to a depth of about onefourth of an inch.

In considering this process, Professor Faraday has always looked upon the excess of corrosive sublimate in the parts towards the exterior of the timber as a most important condi