ON PREVENTING THE DECAY Of WOO». 329 



of England and Scotland; and the inhabitants of the still preserved by 

 more northern regions constantly preserve their food, by ^iffpf^Li. 

 freezing, unchanged through the longest winters. The ge- sture. 

 latinous and other soluble parts of animal substances, when 

 extracted by boiling, and kept in a soft moist state, Terj 

 readily putrefy. But if the same matter be dried by a 

 gentle heat, and secluded from moisture and air by being 

 kept in bottles or metallic cases, 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, reducing them to a substance like 

 leather or horn, which proves to be unsusceptible of future 

 decay from putrefaction. So also entire human bodies, bu- 

 ried in the arid sands of those countries, have often been, 

 found converted by exhalation and absorption of their na- 

 tural moisture into a dry hard sort of mummy, incapable of 

 any farther change from the agency of those causes, to 

 which, in such situations, they are exposed. 



Similar causes produce the same effects on wood. Even Timber long 



under less riffid circumstances of this kind, as in the roofs P reserve ? m 



& ' large buildings, 



and other timber of large buildings, it continues for an 



astonishing length of time unchanged; witness the timber 

 of that noble edifice Westminster Hall, built by Richard II 

 in 1397; and the more extraordinary instance quoted by 

 Dr. Darwiu, in his ingenious work the Phytologia, of the 

 gates of the old St. Peter's church in Rome, which were 

 said to have contiuued without rotting from the time of the 

 emperor Constantino, to that of pope Eugene IV, a period 

 of eleven hundred years. On the other hand, wood will 

 remain for ages with little change, when continually im- 

 mersed in, water, or even when deeply buried in the earth ; underwater, 

 as in the piles and buttresses of bridges, and in various mo- dn m eart ' 

 Tasses. These latter facts seem to show, that, if the access of 

 atmospherical air is not necessary to the decay of wood, it 

 is, at least, highly conducive to it. 



In posts fixed in the ground and exposed to the weather, Decays soon *>» 

 we constantly find that part soonest decay, which is j ust *f *{j^ gVoSnd, 



above 



