Humphrey: Durability of American Woods 
87 
TABLE IV 
Durability of Heartwood after 6 Months’ Test 
[An asterisk (*) denotes that the blocks became too wet for a fair test.] 
Kind of Wood 
Flask 
Oven- Dry 
Weight (Grams) 
Loss 
Remarks 
No. 
Before 
Test 
After 
Test 
Grams 
Per 
Cent. 
Western hemlock 
14 
7.14 
330 
384 
53.8 
Friable when dry. 
Engelmann spruce 
14 
7-25 
3-55 
3-70 
SI-0 
Friable when dry. 
Sitka spruce 
14 
6.29 
3-6o 
2.69 
42.8 
Friable when dry. 
Red spruce 
14 
6.84 
2.90 
3-94 
57.6 
Friable when dry. 
White spruce 
14 
6.13 
3-20 
2.93 
47-9 
Friable when dry. 
Alpine fir 
14 
6.7s 
3-55 
3-20 
47-4 
Friable when dry. 
Grand fir 
14 
7.04 
3.8s 
319 
45-3 
Friable when dry. 
Grand fir 
14 
5-65 
2.86 
2.79 
49-4 
Friable when dry. 
Noble 
14 
7.87 
4-85 
3-02 
38.4 
Friable when dry. 
European laich 
14 
10.04 
7.48 
2.56 
25 -S 
Well rotted in spring- 
wood. 
In drawing conclusions from the above data the moisture con- 
dition of the test blocks should be given due weight. Such as 
became obviously too wet for decay to progress at its maximum 
rate have been indicated, but certain of the other blocks may have 
varied around their optimum sufficiently to influence the results 
somewhat. There is a strong indication that certain of the woods 
vary in their hygroscopic properties, and would thus absorb more 
moisture in a given time than other woods placed under similar 
conditions in the same flasks. 
In order to assist toward a proper conception of the prevailing 
moisture condition the records made at the time of opening the 
flasks are presented as follows : 
Flasks II, 12, 1 6, and 17 were undeniably too wet. The re- 
sults on flask 17 have not been used and flasks ii and 12 have only 
been employed insofar as they appear of some value in forming a 
tentative estimate of durability. 
In flasks i, 2, 4, 7, 8, 9, 10, and 18 the moisture conditions were 
fairly good but rather in excess of the optimum. 
Flasks 3, 5, 6, 13, 14, and 15 were in excellent condition, flask 
13 apparently being the best of all. 
In flask 10 the blocks of white cedar and California juniper 
were lying close to the top and were only slightly overgrown. 
The growth of the fungus was very luxuriant in all and the 
