512 



AUXILIARY FOREST INDUSTRIES. 



upward pressure equivalent to that of 10 or 12 feet of 

 water.* Tr.] Boucherie discovered that a pressure of one 

 or two atmospheres applied at the transverse section of a 

 log is sufficient to expel the sap and replace it by another 

 liquid. 



Stems or poles, with their bark intact, are placed nearly 



Fig. 306. Boucherie's method of injection. 



horizontally (Fig. 306, a, a) on a timber framework; the 

 liquid (1 part sulphate of copper to 100 parts of water) flows 

 from a vat I, which is supported on a trestle 26 to 32 feet 

 high, passing by the pipe in into the conducting tube n under 

 the ends of the logs, it enters the logs through the gutta- 

 percha tubes p, each tube having a separate tap. In order 

 to prevent the liquid from escaping by the anterior section 

 of a log, a piece of hempen rope is placed round its periphery 



