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about seven hundred and fifty feet above sea level. The gathering 
ground is chiefly mountain pasture and bare rocks, the substrata 
being Skiddaw Slate. The sample of water for analysis was 
obtained from the principal spring, above the site of the reservoir. 
We shall now turn to the consideration of the analyses of these 
waters, a copy of which I have placed before you. 
The impurities in water which may be wholly dissolved, or 
partially dissolved and partially suspended, consist of two kinds, 
namely, “inorganic,” or mineral matter ; and “organic,” vegetable, 
or animal matter. The former, if free from poisonous metals, and 
present in not too large a quantity, can do no harm. ‘The 
“organic” matter, however, if derived from sewage, may contain 
germs of those fatal diseases—Cholera, Typhoid fever, etc. It is 
therefore to the organic matter in the water, we must turn, in order 
to arrive at a conclusion as to its fitness for domestic use. And 
those who are acquainted with the most recent sanitary knowledge, 
are aware that it is the quality, rather than the absolute quantity 
of organic matter present, that is the most important factor in 
determining the wholesomeness of drinking water. Unfortunately, 
no process is known by which we can determine chemically the 
presence of these disease germs; and the microscope fails to 
reveal them. ‘This much we do know, however—these germs are 
always associated with animal organic matter, never with pure 
vegetable organic matter. 
A water may therefore contain large quantities of vegetable 
organic matter, such as peat, and yet be quite wholesome; whereas 
a very small quantity of animal organic matter must condemn it. 
But how are we to know to which class the organic matter may 
belong? We cannot even determine, with certainty, the total 
amount of organic matter a water may contain, much less can we 
be sure of its nature. At the best, we can only apply certain 
tests, or determine the amount of certain constituents. 
Drs. Frankland and Armstrong devised a method, some years 
ago, for the determination of the amount of Carbon and Nitrogen 
in the organic matter of water ; for, knowing the relative quantities 
of these two elements, gives some insight as to the origin of the 
