169 
Do not expect to find peaty water when drunk to prolong 
life in a similar way! but I mention this circumstance to show 
that it is an antiseptic, and of a2 very different nature to putrid 
organic matter, which has especially to be guarded against in 
potable water. 
If we wish for soft water from hilly country districts, we must 
be content to have a little organic matter in the form of peat along 
with it, which gives to the water a colour more or less brown, 
according to the quantity present. The colour is objectionable, 
but this is the worst feature. 
Organic matters are capable of being oxidised by certain 
substances which contain oxygen, and based upon this fact we 
have a test which may be applied along with others in the examin- 
ation of potable water. It cannot be used as a decisive test alone, 
but having obtained results by other methods, this is often useful 
as an additional one. (Experiments. ) 
Water, however pure, when exposed to the air in summer, 
may become more or less contaminated with minute organisms ; 
and if organic matter be also present, it will be, by the influence 
of warmth, subject to putrefaction or fermentation. Peat is an 
exception. 
By the influence of these organisms, the putrefactive changes 
rapidly spread, and the multiplication of the organisms themselves 
is almost inconceivably rapid. 
Animal organic matter is characterised by the presence of 
nitrogen, so that we oftentimes find in addition to the free nitrogen 
in absorption in water in the gaseous form from the air, nitrates 
and nitrites, free ammonia, and nitrogen, in combination with the 
elements carbon, oxygen, and hydrogen ; this last class of nitro- 
genous body being well represented by albumen, or the white of 
egg. In analysing a water, it is necessary to look for these forms 
of nitrogen, and we expect to answer whether the water contains 
nitrogenous organic matter, and whether it is putrid. It would 
take much time to explain the details of the analytical processes 
which may be adopted, and, indeed, to attempt to do so here 
would be very unnecessary. Briefly, I may point out, as a general 
