£99 
On Preventing the Decay of Wood . 
called life. When that state ceases, and these properties 
and motions no longer exist, the bodies become sub- 
ject to the chemical and mechanical laws of all other 
matter. 
When perfectly dry, and in certain degrees of tempe- 
rature, both seem to be scarcely capable of spontaneous 
decay. On this principle vast quantities of salmon are 
annually conveyed in a frozen state to London from the 
north of England and Scotland ; and the inhabitants of 
the still more northern regions constantly preserve their 
food, by freezing, unchanged through the longest winters. 
The gelatinous and other soluble parts of animal sub- 
stances, when extracted by boiling, and kept in a soft 
moist state, very readily putrify. But if the same mat- 
ter be dried by a gentle heat, and secluded from moisture 
and air by being kept in bottles or metallic eases, it will 
remain very long without decay. This is the theory of 
that well-known and useful substance, portable soup. 
In the burning climate of Africa, when it is intended to 
preserve a dead animal for food, all that is necessary is 
to cut the muscular parts into thin strips, from which, in a 
few hours, the heat of the sun exhales all moisture, re- 
ducing them to a substance like leather or horn, which 
proves to be unsusceptible of future decay from putrefac- 
tion. So also entire human bodies, buried in the arid 
sands of those countries, have often been found converted 
by exhalation and absorption of their natural moisture 
into a dry hard sort of mummy, incapable of any farther 
change from the ageney of those causes, to which, in such 
situations, they are exposed. 
Similar causes produce the same effects on woodo 
Even under less rigid circumstances of this kind, as in 
the roofs and other timber of large buildings, it conti- 
nues for an astonishing length of time unchanged ; wit- 
ness the timber of that noble edifice, Westminster Hall, 
