DISEASES OF PLANTS. 849 



to heat and moisture, and is said to form a homogeneotis and smooth surface. 

 Since sugar is .odorless and since paving l)loclis treated in this manner do not 

 svA-eat and caii be easily kept clean, their use is believed to be desirable from 

 the hygienic s1iui(l|)()int. 



The seasoning- and preservative treatment of hemlock and tamarack 

 cross-ties, W. F. SiiKurESKK (U. S. Dcpt. A(ji:, Forcxt Hcrr. Circ. 1,32. itp. .?/, 

 flil!^. -'/). — Owing to the increasing scarcity of white oak, hemlock and tamarack 

 are now being considerably used as tie timber. In 1905, 8,(K>(),0S2 tamarack 

 and 1,713,(X)0 hemlock ties were purchased by the railroads of the Ignited 

 States. Ties made from these species last only about 5 years when untreated, 

 hence they are usually treated with some preservative, of which zinc-chlorid 

 is most commonly employed. 



In this circular an account is given of a cooperative experiment undertaken 

 in the spring of 1905 by the Forest Service and the Chicago and Northwestern 

 Iiailway Company, in order to determine the results obtained at the railway 

 company's treating plant and to devise methods for bettering the treatment. 

 Considerable data are given and discussed relative to the methods and results 

 of seasoning and treating, together with the conclusion reached and recom- 

 mendations based upon the results of the experiments. The cost of impregna- 

 tion with zinc-chlorid was found to be 12 cts. per tie. It is estimated that an 

 added life of a single year makes the cost of treatment practicable, and an 

 added life of 5 years secures a saving of ?i(\.?t per cent of the annual charge. 

 Although the absoi-ption of hemlock and tamarack is difficult as compared with 

 Itorous species, the treatment of these timbers results in a decided economy to 

 l)oth the railroads and the forest i-esources of the country. 



During the experiment some 6,000 ties have accunuilated, which were cut in 

 different months of the year, seasoned in different ways, and treated under 

 varying conditions. These ties are to be placed in a trial section of track 

 with a view of putting different methods of handling, treating, and protecting 

 ties to a practical test. The proposed method of procedure is (lescril)ed. 



Preservation of piling against marine wood borers, C. S. Smith ([/. »9. 

 Dciit. A(/r., Forest Hcrr. Circ. 128, pp. 15, //ry.s. .7). — This circular contains the 

 results of a study of the character and extent of damage done I)y marine wood 

 Itorers and of the present methods of i)rotecting piles, and which was made 

 with the view of devising an efficient and cheap method of protection. The 

 kinds of wood used for piles in different regions of this country are enumei-ated, 

 the marine wood borers are discussed relative to their structure and habits, 

 and an account is given of the methods used for protecting movable structures 

 and piling and of their efficiency. 



The conchision is reached that the use of pro)ierly creosoted material f()r 

 piling should be extended. The denser timbei's are unsuitable for the purpose, 

 since it is difficult to secnre a satisfactory penctrMtion of the oil, but timbers 

 of open grain like loblolly pine are easily penetrated and embody all of the 

 characteristics of an ideal pile timber. The extension of their use is recom- 

 mended, since a uniform and satisfactory penetration can be secured with such 

 timbers when properly air-seasoned before treatment, and by the elimination 

 of the expensive " pressure-cylinder " process, 50 per cent or more of the time 

 required for treatment is saved, and there is also a c<»nsiderable reduction in 

 cost. 



As a result of many experiments conducted I)y the Forest Service to devise 

 a cheap and efficient method for the i)reservatlve treatment of linihei- the open- 

 tank method, which has been previously described (K. S. R., 10, ]». 1.50), was 

 evolved. The ai)plication of this method to the treatment of piling is briefly 



