316 Forestry Quarterly 



to a notable extent, for cellulose is attacked by fungi only with 

 great difficulty. In practice, on the other hand, they have fallen 

 to the ground sooner than even untreated timbers, the natural 

 coherence of the wood being destroyed. 



Very recently there has been conducted an extensive propa- 

 ganda for certain secret processes under the names of "Acrol," 

 "Viczsal," and ''Kulba." Referring to pretended certificates from 

 the laboratory for testing materials it is asserted that the strength 

 of timbers treated with these materials is "about 5 to 7 per cent 

 greater," or even 100 per cent greater than that of untreated 

 wood. The chief ingredient of the first mentioned material is 

 an ammoniacal solution of copper sulphate in sodium hydroxide. 

 This, however, attacks the wood fibres rather seriously since it is 

 a solvent of cellulose. The testing laboratory at Berlin, Lichter- 

 felde, to which timbers were submitted for examination, also 

 states that the strength was reduced at least 10 to 15 per cent. 



As for the rest, Acrol, Viczsal, and Kulba have absolutely no 

 greater preservative powers than plain copper sulphate, and cop- 

 per salts have, as tests extended over about 80 years have shown, 

 very insufficient efifectiveness. Ammoniacal solutions of copper 

 salts, especially, were tried out without success as early as the 

 years about 1860 by LeRottier. 



Of all the hundreds of methods of preservative treatment 

 which have been proposed since the year 1800 (the author has a 

 list of patents for wood preservation methods of almost 2500) 

 there are only two which, judged from the standpoint of mining 

 needs, are suitable for use in mining. The one is the treatment, 

 known since 1870, with corrosive sublimate, called after the 

 chemist Kyan who introduced it as a technical process, Kyanis- 

 ing; the other is the treatment with fluorin salts, especially with 

 the Wohlmann salt mixture, originated by the engineer Wohl- 

 mann, which has found a continually widening application since 

 the year 1905. 



