EVERGREENS OF COLORADO 49 



by the Forest Service and this data will be forthcoming doubtless at a 

 near date in the future. 



Our native red cedar has a deserved reputation, where it is known, 

 for its great durability in contact with the soil. This durability is confined 

 almost entirely to the heart wood and doubtless varies in considerable 

 degree with the rapidity with which the tree has grown. Fence posts 

 of this tree have been known to last for a period of thirty-five years in 

 actual service, although this should not be considered as the usual length 

 of time. Twenty to twenty-five years for the medium sized posts is 

 probably a safer average length of service to count upon. Red cedar is 

 becoming so scarce at the present time that very high prices are asked 

 for even small, crooked posts. An examination of the native red cedar 

 posts and stakes on the market will show that in many cases from twenty- 

 five to fifty years has been required to produce one inch of diameter 

 growth. This slow rate of growth and the relatively small number of 

 these trees now available, means that in comparatively few years almost 

 no red cedar fence posts of native growth will be obtainable. 



PRESERVATIVE TREATMENT OF TIMBERS. 



The present and increasing scarcity of our most durable timbers, such 

 as pitch pine and red cedar, is helping to impress the need for some process 

 of making our cheaper but less durable timbers more lasting. A number 

 of preservative treatments have been employed for this purpose for many 

 years in Europe and are being more extensively used every year in this 

 country. One of the easiest and most effective treatments consists in im- 

 pregnating the wood of the least durable and cheaper species with some 

 antiseptic fluid which will prevent the growth of organisms which produce 

 decay in the wood. For this purpose, the commercial article known as gas 

 tar creosote, which is a by-product in the manufacture of illuminating gas 

 from coal and crude petroleum, has been found especially effective. For 

 small farm operations, involving the treatment of from fifty to two or 

 three hundred posts, the material is most effectively used by placing the 

 butt ends of the seasoned posts into a metal tank or other container deep 

 enough to allow the creosote to reach a point at least six inches above 

 the depth to which the posts will be planted in the ground. The creosote 

 is then heated either by a coil of steam pipes or by a fire underneath 

 to a temperature several degrees above that of boiling water. When 

 allowed to cool down during a period of from six to twelve hours, the 

 creosote is forced into the pores of the wood by atmospheric pressure. 

 Posts treated in this way can be expected to last two or three times as 

 long as the untreated wood and where the treatment has been especially 

 thorough, from four to five times the ordinary length of life of the un- 

 treated timber. 



One of the tree products which was at one time of considerable im- 

 portance is tan bark, obtained from the Douglas fir. Since the disappear- 

 ance of the buffalo, however, from this region and the use of tannin 

 extracts together with the diminishing of the supply of this species in this 

 state, the tan bark industry in Colorado is at a very low ebb. 



