558 
POPULAR SCIENCE REVIEW. 
purity of spring water and river water^ as some springs come 
up liiglily charged with objectionable constituents^ whilst some 
river waters present a purity unrivalled by any spring water. 
The great object of every civilized community should be to 
secure pure water^ whether it be derived from springs or 
rivers. Water is so essential to life^ and its deficiency or 
impurity may be so destructive of healthy that the supply of 
water ought never to be dependent on individuals. Like the 
air which we breathe it is amongst the first gifts of God to 
man^ and no man has a moral right to stand between his fellow- 
creature and this essential of his existence, and all arrange- 
ments which exclude the poorest from a healthful supply of 
this agent should at once be modified Not only, however, 
is there a scanty supply of this necessity in many of our large 
towns, but great ignorance prevails of what are the conditions 
which render it impure. 
Water itself, the chemical compound of hydrogen and 
oxygen, of which we have spoken, is always pure ; but it 
has great chemical powers and unites vigorously with other 
agents, dissolving them and holding them in solution. It is 
these substances which act injuriously on the human system, 
and which, not being required there, produce diseased actions 
in the body in order to get rid of them. 
Spring and rain water do not materially differ from each 
other in composition. It may, perhaps, be generally stated 
that spring water presents a tendency to impurity from excess 
of inorganic constituents, whilst river water presents the 
same tendency from the presence of organic constituents. 
It should, however, be recollected that under the term spring 
water two very different sources of supplv are indicated. In 
one case it is applied to springs which bimst from rocks and 
are discharged into rills on the surface of the earth, or to 
water obtained from deep borings in water-holding rocks; 
whilst in another case it is applied to water from wells 
sunk a few feet into the soil, and from which water is 
drawn by means of pumps. Such wells are frequently sunk 
in the midst of towns, and are the depositories of all kinds of 
organic filth from the percolation of drains and surface water 
of the district. 
In referring to the constituents, then, of spring and river 
waters, which are likely to render them impure, I shall speak 
of them together. These substances may be divided into 
inorganic and organic. The inorganic are saline matters which 
are dissolved by the water in passing through or over the 
rocks of the earth, whilst the organic substances are the result 
of plants and animals which have lived in the water, or 
have been introduced by the contact of the water with dead 
organic matter. 
