timbers, crossing plank, car lumber, posts on right of way, etc. In 1928 the railroads used almost 20 per cent of the total timber cut in the United States. Increasing the life of a considerable part of this total timber used, therefore, means a great saving to the railroads. It also means a great saving in the cut of timber from our forests each year. Tie replacements on railroads are decreasing every year, as a direct result of preservative treatment. One railroad has reduced its average annual tie replacements in 20 years from 277 per mile to 83 per mile.

The great saving which the railroads realized by wood preservation led to the use of treated wood by other large industries. A great amount of treated timber is being used for telephone, telegraph, and power poles, docks, piers, wharves, posts, highway bridges, mine construction, etc. In fact, there are few industries in this country to-day using wood for construction purposes that do not preserve a considerable part of it.

In 1909, when figures were first compiled on the amount of wood treated in the United States 519,211,464 board feet were treated. In 1928, this figure had increased to 4.023,844,548 board feet. The last few years have witnessed a very rapid increase in the wood-preserving industry, the volume of wood treated having more than doubled in the 5-year span from 1922 to 1927. In 1928, 220,478,409 gallons of creosote and 23,524,340 pounds of dry zinc chloride were used in this country. In addition 417,953 gallons of miscellaneous oil preservatives and 443,308 pounds of miscellaneous salt preservative were used.

The most striking benefits and economies derived from the use of treated wood are in analyzing data taken from the reports made by the railroads to the Interstate Commerce Commission.

It appears that in 1927, 1,046,951,378 ties were maintained in the tracks of the Class I railroads in this country. They required 78.340,182 ties for replacement purposes, with a value of $105,916,283.

By converting these sums to unit costs it would appear that one tie renewal, at a charge of $1.35 each, was made for every 13.5 ties in track, or, the renewals for 1927 represented the equivalent of an average life of 13.5 years. (Decay is not alone responsible for tie renewals. Quite often ties in road beds subject to heavy traffic and rolling stock wear out through mechanical failure due to rail and tie plate cutting or to becoming spike worn.)

Unfortunately statistics are not available for the years prior to the time that treated ties were used. Service records, however, indicate that the most durable wood which then could be made available economically and used untreated, had an average life limited to approximately 10 years.

Had nothing but untreated ties been used prior to and including 1927, the renewals of that year would have been expected to be 1.046,951,378 divided by 10 or 104.695,138 ties. By subtracting 78,340,182 (actual number of tie renewals) from this figure the number of ties saved in this year, 26.354,956, would be found. It has been estimated that the present cost of a tie in place is around $2; on this basis the ultimate yearly savings would be approximately $53,070,000. Expressed in a daily savings it would amount to some $145,000 saved to the railroads each day in the year.

A few figures on the increased life thus obtained, however, taken from actual service records of timber treated by standard methods, will give an idea of the value of proper treatment.

There are many examples, covering a long period of years, showing the great durability of treated compared with untreated wood, for many purposes. Creosoted piles and timbers in many railway bridges built 30 to 50 years ago are still sound, having required little maintenance, and are carrying the heavy traffic of to-day. If built of untreated material they would have been renewed several times during this period and would undoubtedly have required expensive maintenance in addition.

Sap pine posts treated with creosote and with adequate absorptions of zinc chloride set by the Santa Fe Railroad in southern Texas more than 16 years ago, are still perfectly sound, while similar untreated poles were completely decayed after but a few years in service.

In a number of instances, creosoted wharf timbers have been salvaged and reused in new construction, after 20 or more years of service, when the structures became obsolete and were replaced by modern structures to meet present-day conditions.

Creosoted ties in some electric railway lines also have been salvaged after 15 to 20 or more years of service and reused in new construction. Practically all ties used by the important steam railroads are treated to prevent decay; and the renewals have been greatly reduced, with considerable saving because of proper treatment.

Treated roof timbers in textile and pulp mills are giving excellent service, where untreated wood, because of the very severe conditions in these locations, has a relatively short life.

Public utility companies have greatly lengthened the life of poles by proper treatment, and records of 30 or more years of service are not uncommon. These poles are in good condition and will undoubtedly give many more years of service. Untreated poles similarly placed would probably have had about half the life thus far obtained from the treated poles.

During the past 10 years or so the State and county highway departments, learning of the excellent service from treated wood obtained by the railroads, have used treated timber to a greatly increasing extent for bridges and culverts; and very satisfactory results are being obtained. (Fig. 10.)

The use of treated timber for fencing, sills, and floors of small buildings, etc., is too recent to permit an estimate of the life that may be expected from these uses. There is every reason to assume, however, that the service being obtained from treated wood in other locations will be duplicated here, or even exceeded, by reason of the less severe conditions encountered.

Economy through proper preservative treatment of wood is not restricted to these large industrial consumers, but can be enjoyed as well by the small consumer. The investment of the average home owner in a house or other building is as great, proportionately, as the investment of a public utility in some particular enterprise, and if preservative treatment is a paying investment for the public utility, it is also a paying investment for the small consumer for purposes where the life of untreated timber is limited by decay or in

sects. The advantage of reduced upkeep applies also to the home owner, since replacement of decayed or termite-eaten portions of the building frequently necessitates much labor and inconvenience.

USES FOR PRESERVED WOOD

Preserved wood has been used extensively for so many years by large industrial concerns, that its application to their purposes is quite generally understood. Its value is recognized for every purpose where there is danger of premature destruction by decay or insects, and where it is desirable that the strength of the wood be retained throughout its service life. Because the use of preserved lumber by the small consumer has been comparatively limited, however, there is considerable lack of understanding of its application to his special needs.

FIGURE 10.-Not only were railway cross ties, telephone poles, and cross arms in this picture given preservative treatment, but highway guard parts and road signs were treated, as Courtesy American Wood Preservers' Association

well.

The recommendation that treated lumber be used in residence construction, has reference only to its use for those portions of the buildings that are in greatest danger of destruction by decay or insects, and which ordinarily are destroyed and must be replaced long before the remainder of the building has begun to show signs of deterioration. These are the portions that are in contact with or near the ground, in damp, poorly ventilated basements, or in contact with other timbers or with masonry, girders, joists, stringers, subflooring, window frames, roof timbers, and shingles. In these locations decay is certain, if moisture accumulates in the wood. The siding of residences is not subject to such severe attack by decay, and if paint is applied at regular intervals weathering is retarded and long life will be obtained. Paint does not prevent decay, however,

FIGURE 11. A modern chicken house, constructed of creosoted lumber which resists the attack of insects, fungi, and vermin.

Wood Preservers' Association

Courtesy American

nor will it prevent attack by termites; and in regions severely infested with these insects it may be necessary to treat the siding as well as the other timbers. If this is treated with water-borne solutions it can then be painted any color desired.

For construction of frame buildings other than residences, such as silos and chicken and hog houses, creosoted lumber for the entire structure is usually recommended. This removes the necessity for painting, and in addition the creosote has a germicidal and sanitary effect, practically preventing infestation with vermin. (Fig. 11.) There is listed below a number of the most important uses and suggested uses for treated lumber. As stated previously, the selection of preservative should be made carefully and after considerable study.

FIGURE 12.-Stock pens constructed of creosoted lumber. Courtesy American Wood Preservers' Association

These tabulations are given to enable the reader definitely to ascertain types of structure and component parts which, it is advocated, should be treated when used. It is not in any way a set of specifications, but is shown only as a guide, with suggestions designed to assist the consumer, builder or architect and other interested parties, in selecting material that will give long life.

Structures in which treated material should be used