PERIODICAL LITERATURE 733 



fully as valuable as that of most pines, so that considerable care should 

 be exercised in selecting a method of working which will yield the 

 maximum amount of resin with a minimum of injury to the tree. 



Narrow faces yield more resin per unit of width than do broad ones, 

 so that in theory several small cuts would be preferable to one large 

 cut. But the work is increased by increasing the number of cuts, more 

 receptacles are required, and more turpentine is lost by evaporation 

 from the relatively greater surface over which the resin has to flow, 

 so that in practice the larger cut is preferable. 



The adze method, which is used in Austria, was the first method tried 

 in Germany. Splettstosser then introduced the groove method as prac- 

 tised in America. This has the advantage that the wound is smaller, 

 the flow is quicker and consequently evaporation less, and the faces can 

 be worked either upward or downward. Splettstosser originally spaced 

 his successive grooves several centimeters apart, in a "herring-bone" 

 pattern, but the American method, which leaves no interval between 

 cuts, IS better, because it makes it possible to work for four years on a 

 face which the herring-bone method would cover in one. 



The Americans, working their faces upward, get less resin than if 

 they reversed the direction. Kienitz' experiments indicate a yield 50 

 per cent greater by working downward. He thinks this due partly to 

 the less likelihood of loss through evaporation and overflow. 



While flasks to catch the resin save much turpentine which would be 

 lost by evaporation from more open receptacles, they are expensive, 

 difficult to empty, and apt to fill with water. Open receptacles will 

 probably be used more for the present. 



Forstmeister Aueroch describes the results of his experiments in the 

 Schollkrippen district. Regarding technique, he discusses the trial of 

 various tools and equipment and concludes that tins driven into grooves 

 in the tree are more satisfactory than the "swallow-nests," which are 

 attached to the outside of the tree, since the latter are subject to exces- 

 sive breakage. Removal of the outer bark (Rotung) preparatory to 

 cutting the grooves should not be done until just before working begins, 

 because increased evaporation or decreased bark pressure, or both, 

 result in decreasing the flow of resin. 



He makes the following notes regarding the influence of various 

 factors on the flow of resin : 



1. Age of stand. The stands studied were from 65 to 100 years old. 

 There seemed to be no difference in yield due to age. 



2. Rate of grozvtii. His experience w^as contrary to generally ac- 

 cepted theory, that quick-growing trees yield more than those of slow 



