ON THE QUANTITY OF WOOD-GUM (XYLAN) 
77 
Fraxinus pubinervis, Bl. 9.7 10.7 
Ultnus 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 J) 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. 
(C 
oniferæ) 
1.742 
2) Thuya obtusa, B. et H. 
( 
» ) 
2-357 
3) Pinus parviflora, S. et Z. 
( 
„ ) 
4.212 
4) Ginkgo biloba, L. 
( 
.. ) 
2.51g 
5) Pinus thumbergii, parlât. 
( 
» ) 
4.560 
6) Abies firma, S. et Z. 
( 
» ) 
O.96I 
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. 
( 
„ ) 
I9.716 
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) Ternstrcemia japonica, th. (Ternstromiaceae) 3.813 
1) All of these were sap-wood except that of Cryptomeria japonica. 
