6 BURTON WATERS—DRINKING AND BREWING. 
I take it that by drinking-water, and of course I mean 
pure drinking-water, we mean water obtained from natural 
or artificial sources, of such a composition that it may be 
daily taken into the human system in reasonable quantity 
without producing any injurious effect. On the other hand, 
any substance in solution or suspension which would, when 
taken either for a short or for a long period have an 
injurious effect on the average human system, must be 
considered as an impurity. 
I need hardly, perhaps, remind this audience that, 
chemically speaking, absolutely pure water is a compound 
consisting of one volume of the gas called oxygen, and 
two volumes of the gas called hydrogen, in such an 
intimate state of union that their characters are entirely 
changed, and it is only by the expense of a very considerable 
amount of energy in some form or other that this compound 
body, water, can be split up into its component elementary 
parts, oxygen and hydrogen. But it is not my object 
this evening to enter into the chemical properties of this 
absolutely unnatural body, pure water. To man, generally 
speaking, water is either sea-water, rain-water, river-water, 
well-water, spring-water, or tap-water, and all these are, 
more or less, mixtures of pure water with other substances, 
As our water supply is a sort of endless chain arrange- 
ment—the sea evaporating and producing rain clouds, and 
the rain accumulating and forming streams and rivers, and 
falling back into the sea—it is rather difficult to decide 
which is the best point in the process to take as the 
commencement. I will, however, take rain-water as the 
primary supply of all our water, and whilst tracing its 
course to the jug of drinking-water, I will endeavour to 
make clear to you how it is, that such a chemically simple 
substance as pure water, becomes such a complicated body 
in the form of ordinary drinking-water. 
