301 On Preventing the Decay of Wood: 
somewhat unphilosophical; unless it shall be found, which 
will scarcely be admitted, that dust of every chemical and 
mechanical quality will equally or sufficiently answer the 
intended purpose., 
Some material of this kind, selected with greater pre- 
cision, may however undoubtedly be useful ; and none 1 
think promises more fairly than siliceous or flinty sand, 
which, so far as we know, is absolutely indestructible, 
and which may be easily procured from the sea-shore, 
and from the currents of the clear rivers and roads in 
Berkshire and other counties abounding with siliceous 
stones. Sand from the sea must first be cleared from all 
saline impregnations by washing in several waters ; and 
any sand may be obtained of the fineness desired, by 
mixing it with water in a tub, and after having stirred 
the whole well together, pouring out, in a longer or 
shorter time, the muddy water, from which the sand 
will settle by its own gravity, in a state fit for use when 
dried. 
More than thirty years ago this subject presented itself 
to my mind, on seeing some water-shoots, which had 
been pitched and painted in the common way, taken 
down in a state of complete rottenness. I had read that 
charcoal, buried in the moist earth, had come down to us 
perfectly sound from the times of the Romans ; and that 
posts long withstood the same moisture, if the part in- 
tended to be put into the ground was charred all round to 
a* certain depth. Impressed with these facts, I deter- 
mined to try an artificial coat of charcoal ; and when new 
water-shoots were constructed, I strongly and carefully 
rubbed them with a coat of drying oil, which I imme- 
diately dredged all over with a thick layer of charcoal 
finely powdered, and contained in a muslin bag. After 
two or three days, when the oil was thoroughly dried, 
and firmly retained the greatest part of the charcoal, I 
