26 ANALYTIC SECT. IV. 
of the skin becomes sufficient to close, in a greater 
or less degree, the orifices of the exhalants, and 
obstructs the sensible perspiration. If a person 
labouring under continued fever (whose animal 
heat is at 105°, and skin tense and dry) be bled to 
syncope, the skin contracts by the reduction of 
the vital force, the aqueous particles of the blood 
ooze from the exhalants, and its whole surface is 
speedily covered with large drops of sweat. I use 
this illustration of dermoid irritability, because it 
is a familiar fact, and daily presents itself to the 
observer. 
xL. Europeans, on their first entering the 
tropics, are extremely liable to suffer from too 
great expansion of the skin, from which arise pus- 
tules, prickly heat, and frequently continued fever. 
The skin is best kept from expanding too much, 
by taking a proper quantity of liquids; the 
evaporation from the surface of the body prevents 
the vital force from being morbidly increased. 
xii. The Lady Castlereagh transport, crowded 
with troops, passed in a few days from a latitude 
where the temperature of the atmosphere,;was at 
36° to one at 90°. The allowance of water to 
each man, was only five pints a day. Two or 
three new cases were daily added to the sick list, 
which increased to an alarming degree. Another 
pint of water was added to the former allow- 
ance, and not another new case of fever occurred 
