378 SCIENCE PROGRESS 



substance. The first experiments with the process were made 

 by the Bavarian Government, but since that time a number of 

 private companies have used this method of treatment. 



Certain newer methods of timber impregnation, such as 

 (i) the senilisation process, (2) the emulsion treatment, (3) the- 

 creo-resinate process, and (4) the Ferrell process, were found by 

 von Schrenk in 1902 to be still undergoing trial. In the senilisa- 

 tion process, which is used by a French company, the wood is 

 impregnated with magnesium sulphate by means of an electric 

 current. The emulsion treatment is an attempt to reduce the 

 amount of the tar oil required. One of the methods of doing this 

 is to employ an emulsion of tar oil made by dissolving various 

 quantities of resin in the tar oil and adding a strong solution of 

 soda lye (NaHO). In the resulting emulsion the tar oil is found 

 in the form of exceedingly minute drops, which remain in the 

 emulsified state for several weeks. The emulsion, when pressed 

 into wood, distributes the tar oil evenly throughout its outer 

 layers. The creo-resinate process is like the emulsion treatment, 

 but instead of adding lye the inventor adds formaldehyde. The 

 wood is first subjected to a high degree of heat, to kill any 

 organisms present in it. After creating a vacuum the impregnat- 

 ing solution is run in. The process is supposed to render the 

 wood absolutely sterile at first, and then to give it additional 

 protection outside. The Ferrell process is of American origin. 

 The inventors state that they can inject various salts, such as 

 aluminium sulphate, sodium chloride, calcium chloride, etc., into 

 timber through its ends. They say that the salts penetrate all 

 the fibres thoroughly, and that they can cause the union of two 

 salts in the wood, forming insoluble compounds. 1 



1 For literature upon timber decay and impregnation, vide the bibliography to 

 von Schrenk's Report. 



