Water in Relation to Wealth and Disease. i 733 
the vessels its store of flesh-food for the nourishment of the 
tissues which it traverses, is due to this fact. Water, however, 
is not only a means of conveying food into the body, and of 
distributing it in and about the tissues, but it also acts the 
part of scavenger by receiving and carrying out of the system 
the refuse matter or products of animal decay. Just as the fire 
dies down and is extinguished by the accumulation of ashes in 
the grate, so health is impaired and destroyed by the accumu- 
lation in the blood of the products of combustion, which are but 
the ashes of the fire of life. Practically it may be said that the 
water, which conveys sustenance from the blood to the flesh, also 
gathers together, in its round, the useless and poisonous waste, 
and carries it from the body. The organs through which 
this office is performed are the kidneys, skin, lungs, and liver. 
If the urine, which makes up one-half of the water passing from 
the body, be examined, it is found to contain various crystalline 
substances — organic and inorganic — resulting from the oxidation 
or burning of the muscles and other albuminoid constituents 
of the organism. These are secreted or separated from the blood 
by the kidneys, and carried out of the body in a large volume 
of superfluous water, which filters at the same time through the 
renal organs. The proportion of water to solids in urine is as 
960 of the former to 40 of the latter. 
As a means of cleansing the blood from impurities, water 
again claims attention in that form of excretion termed sweat. 
In this case it is found escaping through the minute pores of 
the skin. Sweat is not a simple fluid, but like urine is chiefly 
composed of water holding in solution waste material, of which 
the system requires to be freed. This refuse matter comprises 
a small amount of urea in addition to various other compounds, 
of which chloride of sodium or common salt is a conspicuous 
example. 
Besides forming a vehicle for the conveyance of these noxious 
matters from the system, sweat, in passing away from the skin 
in the form of vapour or steam, carries off with it a certain 
amount of animal heat, and thus assists in lowering the temper- 
ature of the body. In this way the overheating influence of 
exertion is largely counteracted. 
The function of water, however, as a means of freeing the 
body of effete or poisonous substances does not cease here, for 
we find it being constantly poured out from the lungs in the 
form of vapour, bearing with it large volumes of a deadly gas 
(carbonic acid) which, like urea, and some other urinary in- 
gredients, is also a waste product resulting from the combustion 
or oxidation of the tissues. 
