found in the ruins of Herculaneum. 197 
had probably been strongly compressed when moist in dif- 
ferent positions. 
The operation of fire is not at all necessary for producing 
such an imperfect carbonization of vegetable matter as that 
displayed by the MSS : Thus, at Pompeii, which was covered 
by a shower of ashes that must have been cold, as they fell at 
a distance of seven or eight miles from the crater of Vesuvius, 
the wood of the houses is uniformly found converted into 
charcoal ; yet the colours on the walls, most of which would 
have been destroyed or altered by heat, are perfectly fresh, and 
where papyri have been found in these houses, they have ap- 
peared in the form of white ashes, as of burnt paper ; an effect 
produced by the slow action of the air penetrating through 
the loose ashes, and which has been impeded or prevented in 
Herculaneum by the tufa, which, as it were, has hermetically 
sealed up the town, and prevented any decay, except such as 
occurs in the spontaneous decomposition of vegetable sub- 
stances, exposed to the limited operation of water and air ; 
for instance, peat and Bovey coal. 
The results of the action of heat upon the different speci- 
mens of the papyri, proved likewise, that they had never 
before been exposed to any considerable degree of tempe- 
rature. 
Various specimens of papyri were heated to dull redness 
in a small covered crucible of platinum to which air had no 
access. Some of the chesnut and most perfect specimens 
lost nearly half their weight, and the very black ones, and 
those containing the largest quantity of white ashes, all lost 
more than one-third, as the following results, selected from 
a number, will show : 
