194 STr Humphry Davy on the papyri 
fragment was too rapidly heated, the elastic fluid disengaged 
usually burst the folds of the MS. and when the heat was 
lowered too suddenly, the layers sometimes split in irregular 
parts, probably from the sudden contraction consequent on 
quick cooling. 
From the products of the distillation of these fragments, 
which were water, acetous acid, ammonia, carbonic acid, and 
much inflammable gas, I inferred, that the papyri to which 
they belonged must contain much undecomposed vegetable 
matter, and could not be purely carbonaceous ; but as there 
were great differences in the appearances even of the few 
papyri in England, which had been presented to his Majesty 
George IV. when Prince of Wales, an opinion on this sub- 
ject was more likely to be correct when formed after an 
examination not only of all the MSS. found at Herculaneum, 
but likewise of the circumstances of the excavations made 
there ; and I had an opportunity, during the time I remained 
at Naples, in two successive winters, to satisfy my mind on 
this subject, and to obtain the information which will be 
given in the next Section. 
2 dly. On the state of the MSS. found at Herculaneum. 
The persons who have the care of the MSS. found at 
Herculaneum, state that their original number was 1 6g6, 
and that 431 have been operated upon or presented to 
foreign governments, so that 1265 ought to remain ; but 
amongst these, by far the larger proportion are small frag- 
ments, or specimens so injured and mutilated, that there is 
not the least chance of recovering any portion of their con- 
tents; and when I first examined the rolls in detail in 
