422 Observations, Sc. on the Papyri 
lst. An Account of some Experiments made in England on 
Fragments of Papyri im 1818. 
In examining, chemically, some fragments of a roll of papyrus 
found at Herculaneum, the leaves of which adhered very strongly 
together, I found that it afforded, by exposure to heat, a consi- 
derable quantity of gaseous matter, which was principally in- 
flammable gas, and when acted on by muriatic or nitric ether, 
it coloured them; and when it was exposed to heat after the 
action of these fluids, there was an evident separation of the 
leaves of the MS. 
Chlorine and iodine, it is well known, have no action upon 
pure carbonaceous substances, and a strong attraction for hydro- 
gen; and it occurred to me, that these bodies might with pro- 
priety be used in attempting to destroy the matter which caused 
the adhesion of the leaves, without the possibility of injuring the 
letters on the papyri, the ink of the ancients, as it is well known, 
being composed of charcoal. 
Having through the polite assistance of Sir Thomas Tyrwhitt 
procured some fragments of papyri on which Dr. Sickler, and 
some on which Dr. Hayter had operated, and by the kindness 
of Dr. Young a small portion of a MS. which he had himself un- 
successfully tried to unroll, | made some experiments upon them, 
by exposing them to the action of chlorine and the vapour of 
iodine, heating them gently after the process. These trials all 
afforded more or less hopes of success. When a fragment of a 
brown MS. in which the layers were strongly adherent, was - 
placed in an atmosphere of chlorine, there was an immediate 
action, the papyrus smoked and became yellow, and the letters 
appeared much more distinct ; and by the application of heat the 
layers separated from each other, giving off fumes of muriatic 
acid. The vapour of iodine had a less distinct action, but still 
a sensible one; and it was found that by applying heat alone to 
a fragment in a close vessel filled with carbonic acid or the va- 
pour of ether, so as to raise the heat very gradually, and as gra- 
dually to lower it, there was a marked improvement in its tex- 
ture, and it was much more easily unrolled. 
Even in these preliminary trials, 1 found that it was necessary 
to employ only a limited and small quantity of chlorine, too 
large a quantity injuring the texture of the layer, and decom- 
posing the earths which it contained; and that the action of 
heat was much more efficacious when the MS. had previously 
been exposed to chlorine, as the muriatic acid vapour formed 
greatly assisted the separation of the Jeaves, and a smaller de- 
gree of heat was required. But in all the trials, I found the 
success absolutely depended upon the manner in which the tem- 
perature 
