30 FORESTRY [BoT. Absts., Vol. IX, 



191. Passler, Johannes. Die Bedeutung des Eichenholzes in gerberischen Beziehung 

 und die daraus hergestellten Eichenholzausziige. [Oak v/ood and oak wood extract in the tan- 

 ning industry.] Forstwiss. Centralbl. 42 : 241-249, 306-314. 1920.— Production of tannin from 

 oak wood began about 1883 in Slavonia and Croatia, developed later in France and North 

 America, and during the war was tried in Germany. Results of analyses are given which show 

 that the tannin content increases with age of the tree, and is greatest in the lowest part of 

 the bole. Sapwood contains very little tannin; the greatest amount is in the outer layers 

 of heartwood. Young trees (under 20 years) contain too little tannin to be worked profitably. 

 Tannin content of at least 5 per cent (air-dry weight, moisture content 14.5 per cent) is ne- 

 cessary for profitable operation, but the amount present varies from about 1 per cent in young 

 sprouts, to 13 per cent, rarely exceeding 9 per cent. — The method of making the extract is 

 described, and compositions of various extracts are given. Oak wood extract, which is differ- 

 ent from oak bark extract, is very similar to chestnut wood extract, and gives about the same 

 results. It is generally used in combination with chestnut, quebracho, or spruce extract. — 

 W. N. Sparhawk. 



192. Rattinger, K. Die Holzvorrate der Pacifischen Nordwestkiiste mit besonderer 

 Beriicksichtigung von Britisch-Columbien und des siidlichen Kieferngebietes der Vereinigten 

 Staaten. [The wood resources of the Pacific Northwest.] Forstwiss. Centralbl. 42: 293-305, 

 360-374. 1920. — The forest regions of Canada are described in some detail, and more par- 

 ticularly the Pacific Northwest. For the latter region, including both northwestern U. S. A. 

 and British Columbia, the stands of timber, annual cut, and possible cut, are discussed. 

 The markets for the 2 parts of the region are compared, showing that of the northwest coast 

 woods supplied to countries bordering on the Atlantic Ocean, the United States furnishes f, 

 while it supplies | of the exports to countries bordering on the Pacific (excluding California). 

 The Pacific Northwest and the southerfi yellow pine regions are compared with respect 

 to amounts of standing timber, annual cut, and annual growth, and the conclusion is 

 drawn that southern pine will soon cease to be a serious competitor of the northwestern 

 woods. — W. N. Sparhawk. ' 



193. Raux, Marcel. Le calcul de la perte de valeur d'avenir et la question des reparations 

 forestieres. [Calculation of the loss of future value and the question of forest reparations.] 

 Rev. Eaux et Forets 59: 1-10. 1921. — Official instructions for determining the reparations 

 due from Germany as a result of forest destruction in France provide for including in the 

 estimated damage the loss of future value in the case of trees or stands destroyed prior to the 

 normal age of exploitation. A simple method of determining this loss without the use of com- 

 pound interest formulas is as follows: Estimate the volume, and from this the value, of the 

 tree on the basis of its diameter in 1914 and of its normal diameter at maturity (assumed to 

 be 40 cm.). The difference between these values gives the gross loss in future value; and this 

 gross loss divided by the ratio between the value at maturity and the value in 1914, gives the 

 net loss. While this method avoids any determination of the 2 unknowns, — rate of interest 

 and number of years to maturity, — in the usual compound interest formula, it gives precisely 



the same result, since the ratio between the value at maturity and in 1914, — , is equal to 1.0 



pn for the diameter selected. It is inaccurate to use a single rate of interest as applying to 

 the yield of a tree or stand throughout its life since the rate varies greatly according to such 

 factors as age, size, and estimated maturity. Thus by the method just described, assiuning 

 that a tree increases 5 cm. in diameter every 10 years and that its diameter at maturity is 40 

 cm., the future yield in the case of oak is found to vary from 66 per cent for trees 15 cm. in 

 diameter to 3 per cent for those 35 cm. in diameter. To illustrate the importance of including 

 the loss of future value in reparation calculations, a tj'pical case is cited in which this value 

 amounted to 30 per cent of the value of the high forest and to 62 per cent of the value of the 

 young reserves. — S. T. Dana. 



194. Rebel. Schlagruhe und Riisselkafer. [Suspension of cutting and weevils.] Forst- 

 wiss. Centralbl. 42: 335-336. 1920. — Comments on a recent article by Scheidter (see Bot. 

 Absts. 7, Entry 146). — W. N. Sparhawk. 



