Timbers. 



34 



[January, 1910, 



use to have standard height classes laid 

 down. We, however, are ot opinion that 

 it would be most advantageous, aud we 

 suggest that a suitable standard scale 

 of height classes be drawn up and pres- 

 cribed officially at the same time as that 

 for girth classes. Height is the most 

 reliable indicator as to quality of soil, 

 and once the standard height classes were 

 adopted, it would in time lead to the 

 classification of soils by the height class 

 attained by important species at different 

 ages. 



We trust that this important matter 

 will now receive the attention it deserves, 

 and, if standard classes are adopted, we 

 recommend that the details concerning 

 them be included in the revised edition 

 of the " Glossary of Technical Terms for 

 use in Indian Forestry." It might even 

 be possible to include, from time to time, 

 any special classes indicated by letters, 

 as proposed above in the glossary by 

 means of adenda slips, indicating the 

 area in which the special classes are in 

 force. In this way all confusion would 

 disappear, and in a few years the stand- 

 ard girth and height classes would be defi- 

 nitely known and adopted throughout 

 the Indian Empire. 



WOOD PRESERVATION. 



German and French Process. 



(From the Indian Agriculturist, Vol. 

 XXXIV., No. 9, September, 1, 1909,) 

 Various methods of applying preser- 

 vatives to rail-road ties and telegraph 

 poles have been in practical use in 

 Europe for more than twenty years. It 

 would be difficult to find in any advanced 

 European State a single railway, tele- 

 graph, or telephone line the ties and 

 poles of which have not been impreg- 

 nated with an antiseptic composition, 

 Figures are published relating to twenty 

 German telegraphic lines, the impreg- 

 nated poles of which were set at various 

 intervals from 1877 to 1893. Of those set 

 in 1877 about 35 per cent, were still sound 

 and in use after twenty-six years' 

 service, and of those set from 1891 to 

 1893 there are records of five lines upon 

 which all the poles are still standing. 

 The Americau Consul-General at Ham- 

 burg says that the Bavarian postal 

 service, after thirty years ' experience, 

 certifies that the known average life of 

 impregnated poles in Bavaria is seven- 

 teen years and a half and the German 

 Imperial Administration calculated, in 

 1903, that the known average life of such 

 poles was about sixteen years. In the 

 meantime the work of impregnation is 



being more perfectly performed, so that 

 future statistics will show better results. 

 In France, the Eastern Railway Com- 

 pany announced, in 1889, that in the 

 twenty-four years preceding G7 per cent, 

 ot its untreated oak ties had been re- 



E laced, while only 10 per cent, of such as 

 ad been treated with creosote had been 

 removed. Beech ties properly impreg- 

 nated, according to the Chief Engineer 

 of that Railway, have an average life of 

 thirty-five years. More recent con- 

 clusions reached in the same system 

 were to the effect that 80 per cent, of 

 ereosoted beech ties were good after 

 twenty-seven years of service, while 

 only 54 per cent, of oak ties treated in 

 exactly the same manner were good 

 after twenty-four years of service. The 

 results of impregnation appear so con- 

 clusive and undisputed that it would be 

 futile, says the Consul, to present 

 further details on the subject". In recent 

 years the most useful preservative 

 agents in use have been chloride of zinc, 

 creosote and bichloride of mercury, 

 applied by imbilition, or by impreg- 

 nation by injection forced by the pres- 

 sure of the air. 



This second method of treatment 

 generally consists in placing the wood in 

 closed metallic recipients from which 

 the air is pumped, and the liquid then 

 introduced under high pressure. Until 

 comparatively recently, it was very 

 common to treat wood by injection 

 under pressure of chloride of zinc, diluted 

 with water. While this antiseptic is 

 efficacious, it loses its qualities and 

 becomes hygroscopic. To overcome 

 these disadvantages, creosote was added 

 to the mixture, and under the title of 

 " mixed impregnation " this system has 

 been adopted for the treatment of white 

 wood ties which are too cheap to warrant 

 the use of creosote alone. Hard wood 

 ties, on the other hand, are impregnated 

 with creosote alone, the general effect of 

 which is to close the pores, coagulate 

 the sap, and kill the micro-organ-wood. 

 The use of creosote aloue is quite un- 

 usual in the treatment of telegraph and 

 telephone poles, because of odour, ten- 

 dency to melt and run under the 

 sun, and objection raised by the men 

 employed to deal with them. It is 

 common therefore to use bichloride of 

 mercury 'the French Government use 

 sulphate ot copper), the efficacy of which 

 has been known since the middle ages, 

 when it was used to arrest decay and 

 the action of insects. At the Himmels- 

 bach plant, near Freiburg, this is used 

 in 66 per cent, solution. The wood is 

 plunged into timber or cement recep- 

 tacles, aud there remains from ten to 

 fifteen days. In this plant, moreover, 



