willows: their growth, use, and importance. 35 
willow set in dry soil often last five to seven years. In soils that 
are alternately dry and wet and which freeze and thaw a great 
deal, willow posts are shorter lived, but under such conditions the 
life of any kind of post is much shortened. Posts of the diamond 
willow (Salix cordata) are very durable. More willow than cotton- 
wood posts can usually be produced on a given area in a given time, 
especially if the trees are planted in rows, and willow posts are gen- 
erally set in preference to cottonwood. 
Willow wood is light, fairly porous, and quite easily treated. 
A treated willow post is practically as good as a treated post of any 
other species and much more durable than an untreated post of most 
species. Where good cedar, catalpa, locust, or Osage orange posts are 
obtainable for 20 to 30 cents, it would scarcely pay to use treated 
posts, but in many parts of the Middle West the average price of a 
red cedar post is approximately 40 cents. At this price it would be 
economical to use treated willow posts. First-class willow posts can 
be grown on good farm land for 12 cents apiece and second-class posts 
for 8 cents. These can be treated at a cost of 10 cents. Including 
the cost of peeling at 3 cents each, the cost of first-class creosoted 
posts is 25 cents and second-class posts 21 cents. Willow posts 
should be seasoned 8 or 10 weeks before being treated. Round posts 
are better for this purpose, as the penetration is better in sapwood 
than in heartwood. A willow post properly treated should last from 
12 to 20 years. There seems to be a decided difference in opinion as 
to the value of seasoning untreated willow posts. At one experiment 
station it was found that usually seasoning was of little importance, 
but experience elsewhere does not altogether corroborate this observa- 
tion. At Iowa Falls, Iowa, willow posts cut in the winter, seasoned 
with the bark on, then peeled and set out the following autumn, have 
had an average life of 10 years. At the same place willow posts cut 
in June and set out immediately lasted only 2 or 3 years. At 
numerous places in the prairie region seasoned willow posts have 
lasted 10 years, while most reports of decay in a short time also show 
that the posts were not seasoned. In setting willow posts care should 
be taken to avoid using material with doty heartwood. It may 
easily escape notice because the heart of willow shows very little dis- 
coloration until decay is far advanced. 
TANNIN. 
Willow bark is an important source of tannin in Europe, especially 
in Russia, France, Denmark, and Germany. In Russia it is used in 
the preparation of the finest leather, and combined with birch tar oil 
it produces the well-known scent of Russia leather. Von Hohnel 
states that the crack willow (Salix fragilis) and basket willow (Salix 
viminalis) are the best for this purpose, containing 12 to 14 per cent 
