ON THE QUANTITY OF WOOD-GUM (XYLAN) 



77 



Fraxinus pubinervis, Bl. 9.7 10.7 



Ulnms parvifolia, Jacg 8.9 12.0. 



The samples which I took for the determination of wood- 

 gum were collected from the specimens that belong to the 

 forestry department of our college. 5 grams of the finely 

 powdered air-dried wood'' were extracted with 50 c.c. of 5% 

 solution of caustic soda. After standing for 24 hours with 

 occasional stirring it was filtered and washed with cold water. 

 The filtrate was then mixed with hydrochloric acid until a weak 

 acid reaction was perceptible. The flocculent precipitate was 

 then collected on a weighed filter and dried at ioo°C. to con- 

 stant weight. In this way I obtained the following results : — 



Percentages of wood-gum 

 in the dry matter. 



1) Cryptomeria japonica, Don. (Coniferas) 1-742 



2) Thuya obtusa, B. et H. ( ) 2.357 



3) Pinus parviflora, S. et Z. ( ,, ) 4.212 



4) Ginkgo biloba, L. ( ,, ) 2.519 



5) Pinus thumbergii, parlat. ( ,, ) 4-560 



6) Abies firma, S. et Z. ( ,, ) 0.961 



7) Torreya nucifera, S. et Z. ( ,, ) 2.727 



8) Podocarpus macrophylla, Don.( ) 2.914 



9) Zelkowa acuminata, Planch. (Ulmaceae) 13.240 



10) Castanea vulgaris, Lam. var. 



japonica, DC. (Cupuliferae) 4.776 



11) Fagus Sieboldi, Endl. ( ,, ) 19.716 



12) Quercus acuta, th. ( ,, ) 6.609 



13) Alnus incana, wild. var. 



glauca, Ait. (Betulaceae) 6.852 



14) Phellodendron amurense, 



Rupr. (Rutaceae) 6.586 



15) Magnolia hypolenca, S. et Z. (Magnoliaceae) 10.327 



16) Cladrastis amurensis, B. et H. 



var. floribunda, Maxim. (Legminaceae) 11.964 



17) Melia azedarach, L. var. 



subtripinnata, Mig. (Maliaceae) 2.634 



18) Ternstroemia japonica, th. (Ternstromiaceae) 3.813 



1) All of these were sap-wood except that of Cryptomeria japonica. 



