Periodical Literature. 341 



UTILIZATION, MARKET AND TECHNOLOGY. 



A scale of the conservative effect of dif- 



Treating ferent preservatives has not yet been es- 



Tele graph Poles. tablished, although an attempt was made 



by Christiani to arrive at such a scale 



through statistics from the whole German Empire for 20 years, 



published in Archive fur Post und Telegraphic, 1905. 



This scale, according to the author to be taken with reserve, 

 places tar oils (creosote) first, sublimate of mercury next, zinc 

 chloride next, and copperas last. 



With telegraph poles, says Havelik, it would be presumption to 

 give general preference to one or the other material. All these 

 adhere only superficially to the wood and can be leached out 

 more or less easily, according to local conditions. A study of the 

 statistics of those impregnated with the first and last mentioned 

 materials of the scale lead to the conclusion that where conditions 

 are unfavorable the creosoted poles stand longer than those treated 

 with sulphate of copper, but in favorable locations the latter out- 

 last the former. This would show that the greatest economy is 

 secured by studying the behavior of the different materials under 

 different conditions. 



Untreated poles last from one to seven years, the rot making 

 them break at the ground. Larch poles last usually longer than 

 spruce and fir, and especially when set so as to avoid alternations 

 of dryness and humidity of soil, they last long (over 15 years) and 

 do not decay through rot fungi, but by a different process of dis- 

 integration, which makes them dangerous, because there are no 

 outward signs of decay. Poles treated with copperas also last 

 from one to seven years in unfavorable locations and here they 

 rot through fungi, but in favorable situations, where they last 

 eight to thirty years, they succumb to either of the two modes of 

 decay. In other words, where only the character of the wood and 

 not also the soil conditions would lead to decay the impregnation 

 with copperas is effective. It is useless, on the other hand, to 

 employ this material where soil conditions are the main cause of 

 decay. Here, therefore, creosoted poles should be substituted. The 

 first three years after their introduction the expense would appear 



