_Water, considered from a chemical standpoint_, is a compound substance
consisting of hydrogen and oxygen, in the proportion of two _volumes_
of the former gas to one volume of the latter; or _by weight_ it is
composed of two parts of hydrogen united with sixteen parts of oxygen.
It should be noted that the union of these two gases is effected by
_chemical action_ and not by _mechanical mixture_. Pure water is
transparent, inodorous and tasteless.
Under ordinary conditions water passes the liquid form only at
temperatures lying between 32° F. and 212° F.; it assumes a solid form,
that of ice or snow at 32° F., and it takes the form of vapor or steam
at 212° F.
_There are four notable temperatures for water_, namely:
32° F., or 0° C. = the freezing point under one atmosphere.
39°·1 or 4° = the point of maximum density.
62° or 16°·66 = the standard temperature.
212° or 100° = the boiling point, under one atmosphere.
The temperature 62° F. is the temperature of water used in calculating
the specific gravity of bodies, with respect to the gravity or density
of water as a basis, or as unity.
_Weight of one cubic foot of Pure Water._
At 32° F. = 62·418 pounds.
At 39°·1. = 62·425 „
At 62° (Standard temperature) = 62·355 „
At 212° = 59·640 „
The weight of a cubic foot of water is, it may be added, about 1000
ounces (exactly 998·8 ounces), at the temperature of maximum density.
The weight of a cylindrical foot of water at 62° F. is 48·973 pounds.
_Weight of one cubic inch of Pure Water._
At 32° F. = ·03612 pound, or 0·5779 ounce.
At 37°·1 = ·036125 „ „ 0·5780 „
At 62° = ·03608 „ „ 0·5773 „ or 252·595 grains.
At 212° = ·03451 „ „ 0·5522 „
The weight of one cylindrical inch of pure water at 62° F. is ·02833
pounds, or 0·4533 ounce.
_Volume of one pound of Pure Water._
At 32° F. = ·016021 cubic foot, or 27·684 cubic inches.
At 39°·1 = ·016019 „ „ 27·680 „
At 62° = ·016037 „ „ 27·712 „
At 212° = ·016770 „ „ 28·978 „
The volume of one ounce of pure water at 62° F. is 1·732 cubic inches.
The weight of water is usually taken in round numbers, for ordinary
calculations, at 62·4 lbs. per cubic foot, which is the weight at 52°·3
F.; or it is taken at 62-1/2 lbs. per cubic foot.
Salt water boils at a higher temperature than fresh water owing to its
greater density, and because the boiling point of water is increased
by any substance that enters into chemical combination with it. The
density of water decreases as the temperature increases, since heat
destroys cohesion and expands the particles, causing them to occupy
greater space, where precision is not required; the pressure on a
square foot at different ocean depths are approximate, in the following