328 THE UTILISATION OF WOODLAND PRODUCE. 



the boring a slightly upward slant right into the centre of the 

 heart wood about a foot above the ground, and then plugging 

 up the hole with wood, In Autumn the resin which collects 

 there is scooped out, the hole is again plugged up, and the 

 fresh resin is collected annually for twenty years or more. 



Crude resin is used for distilling oil of turpentine, and the 

 residuum left is rosin or colophony. Distillation takes place by 

 boiling the crude resin in a closed vessel over an open fire, and 

 adding water as the resin melts. As the oil of turpentine 

 evaporates it is carried off along with the steam through a glass 

 cooling- worm into a flask-shaped receiver, the condensed vapour 

 forming water and the oil floating on the top of it. When all 

 the oil has been evaporated the lid of the boiler is removed, 

 and what remains is further boiled until it becomes transparent, 

 when it is poured through wire-strainers to remove impurities, 

 and then run into boxes or casks for transport, where it on 

 cooling solidifies into the ordinary dark-brown rosin. 



On the average, crude resin gives about 15 to 30 per cent 

 of oil of turpentine and 65 to 75 per cent of rosin, with 5 to 10 

 per cent of impurities and loss in distillation. 



Silver Fir and Larch give most turpentine, Maritime and 

 Austrian Pine less, and Spruce least. 



Potashes are now only made in places where wood has small 

 value. The process consists in burning wood to reduce it to 

 ashes, and then extracting the potash-lye from the crude ash 

 in five vats ranged one above the other, and filled for about 

 f with crude ash and J with water. After 3 to 4 hours' soaking 

 the liquor from the top vat is run off into next vat, and so on 

 for the 2nd, 3rd, and 4th vats. The concentrated lye from 

 the 5th vat is then run off into shallow iron pans and evaporated 

 over a furnace until only raw potash, a loose, friable, blackish- 

 brown substance, is left. When the contents of vat 1 have been 

 drenched five times the potash is thoroughly extracted ; then its 

 contents are thrown out, fresh ashes are put in, and it is made 



