ON ABSCESS. 
101 
globules float. In veterinary as well as human practice, it is often 
of consequence to distinguish pus from mucus secreted by an in- 
flamed mucous membrane, and some specific character established 
for this purpose. The common test is, the circumstance of mucus 
swimming on the surface of water, whilst pus, from its specific 
gravity being greater than water, sinks, and becomes partially 
mixed with it ; and, provided our history of the disease, together 
with the several attending phenomena is correct, by this test we are 
enabled to decide. But there are cases in which this test would not 
be sufficient. The mucous membrane of the bladder, for instance, in 
a state of irritation, secretes a fluid which always sinks in water, 
yet at the same time very much differing from pus in character. 
Inflamed mucous surfaces also secrete a fluid, in every stage from 
a frothy watery consistence or albuminous and viscous mucus to a 
homogeneous, friable, cream-like matter, and more frequently to a 
muco-purulent liquid, having the appearance of both mucus and 
pus in a greater or less degree. The best manner of testing these 
two fluids is to press them separately between two plates of glass, 
and afterwards separating the plates : the fluid of pus will attach 
itself to the surfaces of the glass without any adhesive elasticity, 
and more in the form of small globules, whilst that of mucus is ex- 
ceedingly viscous and adhesive, a property of which pus is wholly 
deprived, and serves to distinguish, in a very intelligible manner, 
the difference of character in the two fluids, and that more complete- 
ly than any other feature they present. If farther test is required, 
pus may be dissolved in dilute sulphuric acid, and from which, on 
the addition of water, a plentiful precipitate is produced; but when 
mucus is thus treated with dilute sulphuric acid and water is added, 
whitish filaments form on the surface of the menstruum. In a part 
undergoing the early process of suppuration, and the intersecting 
tissue forming the partitions between the incipient purulent collec. 
tions is losing its vitality and dissolving in the fluid effused, the more 
dense tissues, and the nerves and vessels traversing the part, resist 
for a time the disorganizing process, constituting frsena or isolated 
bridles and attachments between the separated walls of the cavity. 
The internal walls of the abscess are generally close in texture, 
more or less reddened, and tomentous; produced by the effusion of 
lymph and accumulated fluid, solidifying the parts by the exercise 
of its distending action, so that the inclosed liquid is completely 
separated from the surrounding textures. The lining membrane 
of the cavity thus produced has all the appearances of a mucous 
surface, especially if the grey layer of pus is removed. Externally 
this membrane is intimately adherent to the adjoining structures, 
whilst its internal surface is opposed to the purulent accumulation. 
Its density and thickness depend on the slowness of the formation 
VOL. XII. o 
