he
matter thus becomes aerated by the air given out by the other part; or if
the ulcer has been opened, so that any part of it has been exposed to the
air for but one day, a hectic fever is produced. Whence the utility arises
of opening large abscesses by setons, as in that case little or no hectic
fever is induced; because the matter is squeezed out by the side of the
spongy threads of cotton, and little or no air is admitted; or by tapping
the abscess with a trocar, as mentioned in ischias, Class II. 1. 2. 18.

In this fever the pulse is about 120 in a minute, and its access is
generally in an evening, and sometimes about noon also, with sweats or
purging towards morning, or urine with pus-like sediment; and the patients
bear this fever better than any other with so quick a pulse; and lastly,
when all the matter from a concealed ulcer is absorbed, or when an open
ulcer is healed, the hectic fever ceases. Here the absorbed matter is
supposed to produce the fever, and the diarrhoea, sweats, or copious muddy
urine, to be simply the consequence of increased secretion, and not to
consist of the purulent matter, which was supposed to be absorbed from the
ulcer. See Sudor calidus, Class I. 1. 2. 3.

The action of the air on ulcers, as we have already shewn, increases the
acrimony of the purulent matter, and even converts it into a weaker kind of
contagious matter; that is, to a material inducing fever. This was ascribed
to the union of the azotic part of the atmosphere with the effused pus in
Sect. XXVIII. 2. but by contemplating more numerous facts and analogies, I
am now induced to believe, that it is by the union of oxygen with it;
first, because oxygen so greedily unites with other animal substances, as
the blood, that it will pass through a moist bladder to combine with it,
according to the experiment of Dr. Priestley. Secondly, because the poisons
of venomous creatures are supposed to be acids of different kinds, and are
probably formed by the contact of air after their secretion. And lastly,
because the contagious matter from other ulcers, as in itch, or small-pox,
are formed on external membranes, and are probably combinations of animal
matter and oxygen, producing other new acids; but further experiments must
determine this question.

It was thought a subject of consequence by the Aesculapian Society at
Edinburgh, to find a criterion which should distinguish pus from mucus, for
the purpose of more certainly discove