ANTISEPTIC TREATMENT OF WOOD. 



513 



and a board (d, d, Fig. 307) placed over the rope and pressed 

 firmly against the log by a press h and two tension screws 

 and nuts. The section of the log, the board d and the piece 

 of rope placed in a ring between them, enclose a hollow space 

 with which the gutta-percha tube communicates by means of an 

 oblique auger-hole bored in the log. The solution of sulphate of 

 copper flowing from the vat d, with a pressure due to its height 

 above the ground, is therefore driven into the log and expels 

 most of the sap, which issues from the smaller end of the 

 log, at first pure but eventually mixed with the injecting 

 solution. This waste liquid flows into a wooden trough s, 



:'.'7. Method by injection. 



and then is conducted to the tank K, which is provided with 

 a filter to exclude impurities [and also a basket full of crystals 

 of the injecting substance in order to maintain the strength 

 of the solution Tr.] . The liquid in K is then pumped back 

 into the vat b by the pump w. Instead of forming the hollow 

 space at the base of the log by means of a piece of rope, 

 Oesau used a metallic vessel like a round, shallow box, the 

 sides of which are sharpened so that they can be driven into 

 the base of the log with a few blows of a hammer, whilst 

 there is an orifice in the base of the box into which the tube p 

 is screwed. 



[Boppe states that long logs in France are injected by being 

 sawn nearly across at their middle (Fig. 308), so that a 



F.U. L L 



