[Vor. 7 
66 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
This relation of the moisture content of wood at various rela- 
tive humidities has been demonstrated for other woods by 
workers at the United States Forest Products Laboratory located 
at Madison, Wisconsin. This work is reported in “Wood in 
Aireraft Construction” (1919) which was prepared by the above- 
mentioned laboratory for the United States Navy Department. 
The five woods worked with were Sitka spruce, black walnut, 
white oak, yellow birch, and ash, and the maximum moisture 
content at 100 per cent humidity ranged from about 29.5 to 
30.2 per cent for Sitka spruce to about 36.7 per cent for ash. A 
report by Pfeiffer on the physical properties of several Javanese 
woods includes a study of their moisture contents at various 
atmospheric humidities. The maximum moisture contents of 
the various woods at 100 per cent humidity were as follows: 
Tectona grandis (teak wood), 21 per cent; Ensideroxylon Zwagert, 
22 per cent; Shorea sp., 24 per cent; Dipterocarpus sp., 23 per 
cent; Shorea sp., 30 per cent, and Alstonia sp., 25 per cent. The 
specific gravities of these woods were .64, 1.04, .88, .64, .41, and 
.34, respectively. Although the order of increase in maximum 
moisture content in these Javanese woods is not in exactly the 
same order as the decrease in their specific gravities, there is a 
tendency in that direction. Of course, a direct relation through- 
out could not be expected because of the great differences in 
morphological and physical structures between various species. 
Resin CONTENT IN RELATION TO MOISTURE ABSORPTION 
The data on this subject as presented in tables 11 and Iv and 
illustrated graphically in the curves shown in figs. 2 and 4 are 
self-explanatory and for the most part need no discussion. How- 
ever, there are a few points of interest which might be discussed 
briefly. In the lower part of the curves, where the relative 
humidity is less than 50 per cent, the points representing the 
highly resinous samples of wood show no deviation from the 
moisture curves of those samples of wood containing less than 
5 per cent resin. Above 50 per cent humidity, however, 
there is a gradual deviation of the curve representing highly 
resinous specimens. This moisture curve is lower than that 
representing specimens containing less than 5 per cent resin. 
This illustrates the fact that resin actually has a water-proof- 
